Check
http://leagueofbikepolo.com for most bikes
Right now im running a new eighthinch scrambler v3 with rear brake/freewheel 34/20 for polo and 34/16 for riding around. (will get pictures up tonight for you) Still getting used to it coming from dual brakes. Used to have big ol downhill bars/fixed gear and sucked butt in Charleston because everyone was faster than me and I could not reach over my left side. Previous set up is a dawes sst Frankenstein bike.
Lots of people have started ordering custom Marino bikes. I havent seen one yet because we're not at that level yet. Most I see use anything cheap. Garage sales, pawn shop, and trash bin mountain or road are where it's at!