It is actually quite easy to handle payments by yourself. You can go direct with PayPal, Amazon FPS, and Google Checkout, or go through a service like Kagi, Pl

It is actually quite easy to handle payments by yourself. You can go direct with PayPal, Amazon FPS, and Google Checkout, or go through a service like Kagi, Plimus, etc. which will abstract it even further. However, I would expect most web application developers to be experienced enough web programmers, that setting up a payment processor would be about 1 hour of work. ;)