If it mainly is marketed to existing clients, why even use eBay? ย PayPal has some very ย very easy to use mercahnt tools for free where you can either add "buy" a standalone item or shopping cart where multiple items can be ordered together and all purchased in one transaction. ย If you put your storefront on your own site rather than eBay it will be easier for people to find and no monthly ongoing fee, regardless of how small it is, ongoing fees add up.I've used PayPal on my site for gift certificates - ridiculously easy to set up.