What a bunch of whining!
It's a JEEP. Jeeps don't need no stinking heater.
Seriously, The only time I ran into a similar situation was with my Honda Prelude SI, that needed an expensive ( $300.00 +) thingy in the throttle assembly that Honda might but probably couldn't find.
So my mechanic looked around and found a "Honda Only" salvage place that sold it to him for around $100.00.
Maybe there is a Jeep (name your model) Salvage place you can find.
Every one I know of only had the 99-03 version.
All in all, it wasn’t a difficult fix once I really dug in to it.