I need a simple automated Google Checkout script. Once a user is logged in they can upgrade their account to 'subscriber' status by purchasing a subscription. They should be able to select the quantity (in months) to subscribe.
Once they've paid and the payment has cleared without anyway to cancel the order Google Checkout should post back and then the script should simply update the database.
I'm fluent with PHP and can do everything except the automation side of things. All the design and database updating (etc) is fine, I just need the callback stuff handled. I have done this with PayPal and Onebip fine.