The answer is
yes if there is a good chance shoppers will follow links to view other items you are selling and if you take advantage of the cross-promotion tools eBay provides exclusively to eBay Store owners. But before getting into that here are some important eBay Store facts to understand:
What are eBay Stores
eBay Store vs. Shop
At eBay USA, Canada, and Australia they're called eBay "Stores". At eBay UK and other eBay locations they're called eBay "Shops". They are all referred to here as "stores" and essentially all the same thing.
Just so you know: Owning an eBay Store is not required for selling on eBay
Your general on-line buying experience might lead you to believe owning your own store or web site is required for selling. And, when you pay extra for something, such as the (currently) $15.95 per month premium to own an eBay Store (USA), you would naturally expect automatically improved sales. Neither, however, is true of eBay.
You can be successful without owning a store and for most sellers owning a store is an unnecessary expense. That will become clear as you read through this page.
eBay Store Pages vs. Item Listing Pages
eBay Store Pages are custom pages sellers may create and publish as a part of their eBay Store, including one for use as a store home page. Those custom pages are similar in concept to eBay About Me pages in that items can not actually be sold from them. eBay store owners must, just as non-store owners do, create individual item listings.
Whether or not you are a store owner, there is no difference in how item listings are created aside from the ability to assign them to categories - an advantage discussed below in "making eBay Store ownership worthwhile" below.
"Core" vs. "Store Inventory" Listing Format
On July 19th, 2006 the president of eBay made an announcement titled
Resetting the Balance of the eBay Marketplace - a must read for anyone considering opening an eBay Store.
What we have been told is that the store inventory listing format is less favored by eBay than auction type listing formats and eBay Store sellers can expect that any items listed in store inventory format will get much less exposure on eBay than the other listing formats.
The store inventory listing format which seems very attractive because it is relatively inexpensive, actually isn't such a deal after all. It's up to the store owner to promote those listings as discussed in "making eBay Store ownership worthwhile" below.
Making eBay Store ownership worthwhile
Construct Categories Cleverly
The primary advantage of store ownership is being better able to direct shoppers from one of your item listings to your other items for sale. In turn, that is largely dependent on how you construct your categories. For every seller and with different types of items for sale it will vary but the goal is to create category names that are helpful from a shopper's point of view as opposed to simply being used for your own organizational purposes. Here's an example:
Let's say you sell woman's dresses and you sell a variety of sizes and styles. Well, women will likely be shopping in one of two ways, by size or by style so it would be best to provide them with both methods for finding them. Because every item you list can be assigned to two different store categories that's possible. You could create categories representing all the sizes you sell such as "Size 8 Dresses", "Size 10 Dresses", etc. and another set of categories such as "Party Dresses", "Formal Dresses", etc. and when you are selling a size 10 party dress put it into both the size 10 dresses category and the party dresses category.
You'll then you have the opportunity to direct shoppers to either category for their convenience in finding what they are looking for by including links to those categories in your item listings such as these:
"See our other size 10 dresses here"
"See all of our party dresses here"
Furthermore, if you use the listing frame (discussed further down) shoppers have their own way of finding what they want in a manner that suits them.
Use eBay Store Custom Pages Cleverly
Custom Pages can be used very similarly to categories as a means of directing shoppers to other items you are selling. eBay provides Special HTML Tags for use in eBay Store Custom Pages here:
http://pages.ebay.com/help/sell/stores-tags.html
Among those tags is the ability to embed a list of your items for sale into a custom page based on a variety of criteria including price, key words in titles, and category.
Let's extend the example of women's dresses to being able to display items by designer. Because the dress designer is usually an important part of item titles for high fashion dresses you have key words to work with. Provided you always use the same exact wording for the designer in item titles, you could create a custom page that shows all of your dresses by one designer. The eBay HTML tag to use for Pierre Cardin would be:
{eBayStoresItemList KEYWORDS="Pierre Cardin"}
When creating a Custom Page you'd type or copy and paste that into the page where you want the list to appear (in FreeForm you'd put it into a Code Input Area). When the page is done and published as an eBay Store page you can then, in each of your item listings for dresses designed by Pierre Cardin, put a link like this:
"See all of our dresses designed by Pierre Cardin"
which leads to the custom page. Just like categories, the items shown in that page will automatically be updated by eBay to contain only your current items for sale that contain Pierre Cardin in their titles. So, with our dresses we now have three different ways of providing shoppers with a means of getting to other dresses we have for sale. Each of the ways is relevant to the desires of the shopper in relation to the item listing they have already visited. That's what is important - providing links that make sense to shoppers who have landed in any particular one of your item descriptions.
Use the Listing Frame option for your item listings
When managing your store you'll find "Listing Frame" under the heading "Marketing Tools". When you choose the option of including a "left navigation bar" your store categories will appear in to the left of each and every one of your item listings on eBay. If you have named your categories cleverly you will have provided those who visit any particular one of your listings to also visit your store to see what else you have for sale in the category of what they are interested in. In other words, provided you don't have too many categories they'll be able to see on their own where to shop further.
In Summary - Is an eBay Store right for you?
Just owning a store is not enough by itself to help your sales. eBay is geared to present lists of items being sold and those lists are presented without regard to whether the seller is a store owner or not. In effect then, each individual item listing you create is a separate front door to your eBay Store. Hardly anyone will ever actually be arriving through the storefront itself. What that means is an eBay store is only useful if you are able to take advantage of the ability to link from one listing to others effectively. Success accomplishing that, in turn, is largely based on whether or not, at any given time, you have other closely similar type items to link to. For example, a shopper is very much more likely to follow a link from an item listing for a watch to other watches you are selling than they would be to follow links to other types of jewelry. So, you'd need to be selling lots of watches for best results.
If you do have lots of watches to sell (many similar items), then you also have the opportunity to list many of them using the less expensive inventory format and use some listings in the (more expensive) auction format as gateways to the inventory items using the techniques discussed above. Without having enough similar items to list, however, you would not be able to take advantage of that opportunity to save on eBay selling costs.
I mentioned using eBay Store Custom Pages similarly to categories but supposing you are able to get people to visit them from your listings they also have other great potential as information pages, promotional pages, pages you can link to from newsletters, etc. If you sell high dollar items those types of pages could, by themselves, be worth the monthly eBay Store fee. Without owning a store you only get one "About Me" page on eBay to use for that type of content.