I offer a similar service via BitBuffet.com (I own/run the site). It's similar to e-Junkie or Payloadz. Basically, you upload the PDF to us, point your PayPal's

I offer a similar service via BitBuffet.com (I own/run the site). It's similar to e-Junkie or Payloadz. Basically, you upload the PDF to us, point your PayPal's IPN point to us and we deliver the PDF to purchasers via email (we have a nice short walk-through on how to do this). As a matter of principal, we don't offer DRM of any sort, which might be a deal killer for you. You could probably build your own system to do this (just grab the POST variables from PayPal IPN response and send off emails, validate codes, etc...), but if you want to check us out, email me at contact at bitbuffet.com and I'd be happy to extend your trial for however long you like (the default is 7 days). Offer applies to any interested HN'ers of course!