At the beginning of the film, before the first race the racers talk about the bet. They agree on "35 large" ($35,000). Then they proceed to hand over the cash to one guy to hold it. Thing is, none of them gives anywhere near $35k. The wads of money they hand over, assuming $100 bills, is closer to about $2,000 each. WAY short of the bet.
And they all seemed to have the correct amount of cash ready when they didn't know the amount. Also, girl said her man needed to pay rent. If you have 35 large then just pay the rent!