Imagining Robin Williams' genie going on the lam after being freed from his lamp. That's the real reason he went off to see the world. He was avoiding a subpoena.
Strictly speaking, the entire game runs on DM mandate. There's no way to parse a wish without it having to go through a human element - and in this case, the DM has very little reason to read the wish charitably - after all, it's being given to an evil outsider.
I would say the "pay market value" bit is a good way to avoid the worst possible outcomes, but there's still the very real chance that the efreet says it doesn't want to play and takes its ball and goes home. Done diplomatically, at least, it's less likely to end in one out for your head/other thematically appropriate body parts.