Add relevant content, and use social bookmarking. Also put a link to your site in your sig in relevant forums.
One way to look at BANS or any ebay store software/script is as an addition to an already built niche website. What you are then doing is adding a store section to your site. Since such a site already should have content, you can build up search engine traffic through the normal procedures, SEO, backlinks, articles, etc. Just make sure your content pages are well linked to your eBay store area. I do not see why directories would reject such a site. Of course, you can start with BANS and add content and create a niche site that way. Think of ways to increase the value to the visitor, besides just selling them something... By the way, looking for a free way to rotate banners on your websites? Check out my thread at http://forums.digitalpoint.com/showthread.php?t=530164
I have a BANS site that actually gets search engine traffic and I've done nothing with it yet not even any extra content. I think I picked a good niche for that one thats the key.