xHTML CSS valid coding, and intergration into OScommerce (a free shopping cart) is what u need here.
My pricing is as such:

xHTML/CSS valid: $30
OScommerce intergration: $270
Total: $300

Alternativly you can have this intergrated into my own custom cart script that will work with paypal and paypal only. This will cost a total of $450, however you will get all edits included to make this work perfectly for you, for example your currency selector etc. For another $50 you can have some javascript thrown in to really make this site stand out from the crowds .