Coder's Block and Braille on Drive-Up ATMs

Q. Why do they have Braille dots on drive-up ATM machines?
A. Since the Braille is required on the ones that are installed in walk-up locations, it is cheaper to only make one model.

At first the above question seems ridiculous, but once you get into "real world" economics, the true answer seems quite logical, doesn't it?

Did you ever get Coder's Block? It's like writer's block - you sit down knowing that you intend to work on something, and, well, for one reason or another, nothing happens. I generally don't ever get this at work -- the pressure of having to produce and being on the time-expense report means that although my performance might go up and down, at least I'm always producing.

However, I do get this when I am working on my own projects, and I've got a bit of it now. I'm working on a prototype "Link Purchase" system that includes an affiliate commission program, and I'm at the part where I need to integrate PayPal payments with IPN (Instant Payment Notification) that will be used to update a paid PayPal transaction into a database, and I'm like "going in circles". I'm trying to make it as generic as possible so all the values can be stored in a configuration file and thus it can be re-used for virtually any type of product or service sale via PayPal. I've got a sandbox account and credentials, and I am basically "ready to go", but...

I keep downloading sample PayPal ASP.NET code (much of which is in VB.NET -- which "could" be part of the problem!), playing with it, and then abandoning it and scouring the Web looking for more. I'm sure I'll break out of the Coder's Block rut, but I wonder what advice experts may have on this subject!

I'm a big fan of "Don't reinvent the wheel" and so far I've found some pretty good open-source implementations of Paypal with IPN notification, but for some reason, they don't seem to want to "fit" this situation. If you have used a particular implementation that you like, feel free to comment here and we'll feature it.

N.B. Rick's link in his comment got chopped by Blogger, so I'll reproduce it here. Definitely one of the better descriptions of how to handle IPN, too. His advice about not using Sandbox and just doing your testing with very small prices is right on the "money".