orcishgamer: I don't know how it works over there but over here they can add charges for software directly to the phone's bill. There's no reason for a credit card to be involved. You might want to make sure that's not the case for your son's phone.
I'm pretty sure that's not the case with the android market over here.
orcishgamer: And it's Android, there's literally a shit ton of free apps out there. What kinds of apps are you thinking of letting him buy?
Primarily games. He likes Airport Mania very much, for instance, and he'll probably want the Android version of Minecraft as well. And if the Amazon ever pull their head out of their ass and let other people besides Americans buy from their appstore, then Plants vs Zombies is a must, both for him and me.
Athenvance: I don't have an Android myself, and I think others can give you better technical help, but one option would be to set the phone up to say, a Visa gift card. They act like a credit card, but as with all gift cards, there's a set balance on the card, and once you use it up, you can't go over.
Edited to add: You should also be able to reload them.
wodmarach: Yeah a visa prepay would be a good way of doing this you can preload it with his allowance each week and he'll learn to budget that way too
I don't think they exist here in Denmark, unfortunately, but I'll look into it, thanks.