First of all, if your CFI ratings and the insurance-minimum multi time are going to set you back $27k, you might consider another school. That's quite steep.

Secondly, you can just get your basic CFI, and then with the money you earn, pay for the other CFI ratings. I'd try to stay in the black as much as possible. Might take a little longer, but at least you'll be better off financially.

Lastly, even if Jet U was cheaper, you still shouldn't go there. You don't want to be one of those guys. There's a reason why most everyone who's ever been a CFI says you learn a lot and should go that route. I think it's true.