Why the .biz domain name? Most people pretty much automatically associate domain names with .com. I believe there is evidence to suggest that people are more likely to trust a store with a .com domain.
Personally, I'd be worried about people typing in my email address wrong, things like that. If you don't already own it I'd make sure you buy the .com otherwise chances are you are going to lose a small percentage of people who have .com automatically imprinted in their brain. (I am one of them
Other than that, personally I think it looks alright aesthetically.
Another thing with ecommerce stores is that of trust, a percentage of people don't like putting card details in so you have to allay that fear somehow. One way is to present security logo's and brag about your ssl, things like thawte, etc
There are always a gazzilion things to say about websites, hope those help you out somewhat.