Well now let's see...
Waldo and Dick are straight out. Waldo's as bent as they come from a mile away, he'd give me away in a second. Dick's terrified eyes give him away. Not only would Senior Prison Warden Mr. Fulton Mackay spot him in an instant, but the yellow-bellied puddle of piss would turn on a dime to avoid jail time himself.
Lainie and Saf are possibilities, however word around the prison yard is that they're depraved individuals. You can tell from their faces, too. They're screws which are TOO bent, and they'd likely become a liability at some point.
I'm going with Kiah. I went ahead and approached her about it already and it turns out my feeling was correct. She is even more willing than I expected, because she's a good girl who has always wanted to be bad, and has spent a lot of time around prison inmates so she knows the ropes. The idea of being involved in the prison contraband trade with a well-respected hardened criminal turns her on. Not only do I feel she will be reliable, but she's willing in more ways than one, if you catch my meaning. Payment, for her, starts with the letter D. Furthermore, she looks clean cut and innocent. No one will ever suspect her. It's a win-win-win.