The expected per-team salary cap for 2008 stands at $116 million. Currently, the Bengals are at $92 million, even after the Andrews franchise tag if I'm understanding things correctly. That leaves around $20-22 million to spend, assuming that the Bengals stick to their usual plan of leaving some extra cash in case of injuries and what not (came in very handy last year). Who would you go after?
Here's some other teams of interest:
Baltimore Ravens: $109.8 million
Cleveland Browns: $99.4 million
Indianapolis Colts: $125.8 million
NE Patriots: $112.9 million
Pittsburgh Steelers: $99.3 million