Shopping Account (Pre-paid account)

[energia]

I have search around here for a while and wonder if anyone know of an already developed module for adding an account to the shop from where all the users purchases are deducted from. If there is not sufficent money on the account, the purchase can't be done.

Im about to develop this module myself, but I don't to invent the wheel all over again (if not needed)

[salbini]

I would be interested in this, if you work out something, can you please let me know?