I think you need a customised list of bookies sooner rather than later. I appreciate your comments about overhead, so add this feature to your premium program to ensure you get paid for that.
Certain bookies can not be promoted in the UK and others can not be promoted to a US audience. A lot of affiliates will simply refuse to have certain pet-hate bookies represented on their websites, because so many affiliate programs are bordering on rogue (even many of the apparently 'respectable' firms). What you have created looks very promising and impressive but to pick and choose the betting companies promoted is a priority imho.