There aren't many ACBL-sanctioned games for cash prizes. Perhaps this is part of the reason bridge is more popular overseas than in the US, it's not clear. There are a few exceptions:
(1) Many clubs offer free games for the winners. Obviously this is not a substantial "cash prize" but it's better than nothing.
(2) Virtually all tournaments offer some sort of prizes. However, usually these are not cash (glasses or mugs are common for example). There are some exceptions (mid atlantic regional offers script for example, and Atlanta nationals gave gold dollars for section tops in national events) but I've never seen a cash award for regular acbl events with value exceeding the entry fee.
(3) Bridge pro tour events. When these started out they had $100 entry fee, and the prize for the winner could be as much as $5000. These both seem to have been reduced (to $20 per session and payout dependent on number of tables). All of these events (to my knowledge) are individuals, which is nice in that it tends to eliminate opportunities for cheating. While good players have certainly participated in bridge pro tour (notably Chris Compton and Adam Wildavsky), most of the top players prefer to play with clients (it's guaranteed money, better paying, if you're on a team you get to practice with your pro partner for a substantial fraction of the deals, and you play against better opponents).
(4) Various events where ACBL sponsors travel. Notable are the Grand National Teams, North American Pairs, Collegiate Teams, and various Team Trials. While in general winners are not given cash, plane tickets and hotel rooms can have substantial monetary value.
Adam W. Meyerson
a.k.a. Appeal Without Merit