Hi Rosaria,
I would suggest buying a hosting package, I suggest going in for
www.v7inc.com, they are really worth the money!
I have worked on them for some of my clients, and they are good.. they really are!
Then Contacting a Web Developer/Designer and getting either Some Shopping Cart system installed/Programmer or getting Os-Commerce and getting it customised! This way you can get your money's worth!
Abhishek