Hi ninth_wave,
They can do it, Vendio has been doing it for years, I switched from Vendio to Auctiva over one year ago because my Vendio fees were about $50-$70 per month, they have an actual store and I loved it. When people would check out from an eBay purchase, it would bring up other similar Vendio Store items that they could add to their eBay purchase via a cart system. Also they have the scrolling gallery just like Auctiva's (the one in the actual eBay listing), on that scrolling window is a link to see more items, it would take you to your Auctiva Storefront, but would only list all current eBay items, however, the person could then click a category or other links and they would then be looking at all your Vendio store items. Plus in the actual eBay listings, if you had click to supersize pics, when some supersized them, there was a link to "see more items" or something like that which took you to the store again (initially displaying only eBay items).
I really liked it and did make some additional sales from the store for which I paid a measly one percent final value fee (to Vendio).
When I first started with Auctiva, they told me they were working on an actual storefront similar to Vendio's, but it's been a while. I don't know how long I can wait, I really want another storefront like the one Vendio has.
Regards,
Rick