I don't know what the other tire on that axle looks like, but if one tire is good and the other as bad as you describe, you're probably better off with something that's not as bad. If you're down to the metal, its getting scary. I know the party line is to keep the tires equal, but in their present condition they can't be very equal. As you say, not everybody can just shell out the cash to go new tires all around.
The best alternative might be to put your snow tires on early. I don't know where you live but winter isn't all that far away in some places. Failing that, maybe get 2 and not 4? An Olds dealer once told me that on my Bravada it didn't matter front to back, only that the tires were equal on each axle. That was 20 years ago and on a GM product, not a Jeep; the new systems may be more sensitive, I just don't know. Truth be told, I tried that on my FWD Patriot (good tires on the front, well-worn tires on the rear) and while I had no safety issues, it did create a nuisance: I think the different axle speeds confused my ECM causing a hesitation problem that went away as soon as I got new tires.
Best bet is to ask a dealer, but its easy for a dealer to tell you what you want to hear.
