Seems like my response got lost in the server move…

The paypal button is not encrpyted but that is because it is impossible for it to be encrypted. A standard encrypted paypal button has no special values assigned to the button, just the basic price and product information. Any time you want to add any real options to the paypal button, you have to take off the encryption on the button so you can utilize all the other html values Paypal accepts.

At the time Market is not set up to accept digital downloads. Depending on your skill level with php, it could be accomplished. It could be accomplished now as well by using a custom field to set the return url after purchase to a file destination, but it would be viewable in the source code, so it probably would work best by integrating with a IPN script, ie setting the return url in the paypal form to your IPN script which would process the customers order and securely deliver the digital items that were purchased.