If you are considering a stand-alone store, try OsCommerce. Amigakit is runnig on it.
All you need is a decent hosting package and a catching domain name prefering to hold the words C64/8bit/retro which makes it easier to target (and have cheaper bids on AdWords).
WIth a little SEO (search engine optimization) your store can be found without even using AdWords.
Contact me if you need any help or advise for setting up the shop or wanna rank in the search engines.
