PayPal website integration

Ok, this is the solution I want implemented in 3 places: 1. Validate the post back to our site using this process: [login to view URL] There are sample php codes in paypal and online 2. If successful, set the session that I need to show that user got upgrade, etc. 3. For testing, I would like a paypal sandbox set up so that I can see it working. 3. Then, I would like it done with a video or screenshots showing that it is working with the live site (as I don't have 2 paypal accounts I can use). Thanks. Please let me know final pricing and time to do so I can select.