Use the Fileatize block to sell your digital files directly from your concrete5 website via Paypal.
Fileatize is the easiest way to sell your digital goods online. You host your files and use Fileatize to create products that your customers can buy.
Your Customers simply click the relevant link. Fileatize does the rest.
The payment is processed via Paypal and, once payment is successful, the purchaser can download the file from your website via Fileatize, so the file's location on your server is never exposed. Cool.
More information on the service can be found here http://fileatize.com/
Examples of 'Fileatize' products. There are various options that you can configure within the block.