Battle net account balance not updating
Players are given a limited number of "beta bucks" to use on currency-based auction house purchases.
These "beta bucks" reflect how Balance might be displayed and/or used when Diablo III is ultimately released, though as with all things in the beta, this is subject to change.
I know I have enough because I have 10.00$ on my account that I've never used and don't even remember why it was on there.
Anyway, if you have any information on why it isn't working, or how to make it work, I'd be extremely grateful.
In general, you will be able to add value to your Balance using your local currency (in EU, for example, players will be able to use Euros, GBP, and RUB).