I looked into this briefly for my forum and neither book offered anything better then the $100 cash I’m giving away for my monthly POD contest. I think Bookmaker offered $100 but the winner also had to deposit $100 which I didnt really like that so I’m sticking with my $100 free cash no strings attached price untill I can find a book to offer something equal or better.
I had a forum a couple years ago and BetRoyal sponcered a contest $250 prize but there was a 10x rollover and the winner had to deposit 50%.