I am confused on developer products. How would you script so that a player could buy one from a gui? I would also like help on converting this money to pp (player points) if anyone knows how to. Thanks.
Basically, :PromptProductPurchase (player, id) method is how you would prompt a player to purchase something.
ProcessReceipt callback is also used to follow up on any incoming/completed purchases. It has many contents including what was purchases (id only), currency and such. There are others that can be explored here.
http://wiki.roblox.com/index.php?title=ProcessReceipt_(Callback)