Yes and no. Yes it is capable of it the no part is it can't handle huge amounts of traffic. If you imagine that a store slowly grows if you took your profits and prepared for an upgrade when needed then it is a totally viable concept. Just stay away from bloated projects and focus on security you could also just host simple pages and have checkout handled by something like paypal for example or google checkout.
http://www.raspians.com - always looking for content feel free to ask to have it posted. Or sign up and message me to become a contributor to the site. Raspians is not affiliated with the Raspberry Pi Foundation. (RPi's + You = Raspians)