Use WP Auctions as a simple e-commerce plugin with the handy Buy it Now Feature. Just set up your auction as you normally would and enter just the Buy it Now price.
The Buy it Now feature asks the buyer for their name, email address and URL, if they have one. Once they enter the information and click Buy Now, they are prompted to check their email for the payment details. As soon as you receive your payment you can ship out your product.
You can put up as many items as you like with this method and accept payments via PayPal.