There are two shopping carts I recommend depending on whether you require drop shipping functionality or not.

Shopping Cart Drop Ship Price Support Setup Required Recommended For
OrderStorm Yes Free, $5/mo, $20/mo  Excellent  Purchase online  drop shipping
Woo  No  Free  Good  Plugin  all other applications
Seriously consider drop shipping.  Packing boxes, labeling, and postage can consume all your time and then some. 

Link to Shopping Cart Workshop Handout