First, I will have ongoing work for a decent wp plugin programmer. Please keep this in mind when placing your bid.
I have a plugin that I'm selling through PayPal and had another programmer write some code with a MYSQL database and phpmyadmin to communicate with PayPal every time a sale was made, so that the transaction ID was now their password to register the plugin. If the registration code isn't entered, the plugin doesn't work. If they get a refund from PayPal, the plugin doesn't work as well.
It works fine, but I need to duplicate it for another plugin I recently had created.
If you're familiar with wordpress and integrating with PayPal this will probably be a very fast, easy job for you. To make sure that I'm working with someone that pays attention to detail, when you bid on this project, please start your bid with the words "I pay attention".
Good luck bidding! =]