I'll have a good look at the IPN stuff and hope I can make some sense of it.
The trouble with PayPal Pro is that the market is so small for the client that he wouldn't be able to justify the extra cost.
Your friends over here at WebAssist! These Dreamweaver extensions will assist you in building unlimited, custom websites.
These out-of-the-box solutions provide you proven, tested applications that can be up and running now. Build a store, a gallery, or a web-based email solution.