PayBets.. I agree with the poster above, I don't want to pay for the bets, I want the bets to pay me. :-D However, there could potentially be some value in development (Perhaps a gambling oriented payment system/method.. however that'd be tough to run, as I'm sure there are several codes you must follow since it pertains to gambling).
As for BetCoins, I think it's catchy, and brandable. For an end user I'd say mid $xx, to low $xxx.
Good luck!