Originally Posted by PornMD

It depends - if putting up only one site with the money, it should probably be a healthy xx,xxx if reasonable CPC term or maybe mid x,xxx if a high CPC term. Enough searches to bring in traffic that would make a difference but low enough so it's not a ridiculous competition term that would be hard to rank for even with an EMD.

It also depends on how targeted a term it is, which ad competition generally helps figure out - better ad competition would tend to indicate the traffic is more straightforward and can be monetized fairly easily.