Well I bought one a month ago for $5k and I'll share my experience and then you can decide. The one I bought was a 1990 and it is pretty clean for its age. A small amount of rust, but really not bad at all. It only has 65k miles on both the frame and the engine. The guy who sold it to me is a part-time mechanic and he had done an engine transplant (still the stock, 4.0 liter straight six). The engine is warranted to 100k miles. Most folks I talked with say that engine is a good, strong, long-life engine. However, I'm really disappointed with my gas mileage: only 13 MPG average so far. The seller had done a number of other repairs and had repainted the truck and wire brushed and sprayed Rhino Liner on the whole underside and bed. The interior cloth and vinyl is in great condition, but needs to be cleaned. The headliner needed to be replaced. The side view mirror needed to be replaced and that is a simple operation, but it turned out to be problematic using aftermarket mirrors.
When I bought, it I knew I needed new shocks and springs (S&S). I did the back end myself and had my mechanic do the front S&S. I knew the steering was loose when I bought it. I replaced the steering stabilizer and it helped, but didn't fix the problem, so my mechanic is replacing the track bar. I've had leaks: replaced the valve cover and transmission lines. My mechanic is doing a dye test to see where the engine oil leak coming from; he thinks it may be the front seal. When i topped off the differential fluids, I learned that the front left axle seal was blown. I'm having my mechanic replace all the front axle seals and the differential bearings for good measure. So one month into this project, I'm approaching $2k in mechanical expenses for what I thought was a nice, clean truck. However, here's my rule of thumb for old vehicles (and sailboats): whatever you pay for it, plan on putting at least the same amount into it for repairs and then hope for the best.
Would I do it again? Yes, I love all the Jeeps. I knew there would be mechanical surprises and I budgeted for them. Several people, including Jeep owners I've met are drooling over it. For prices, scan the internet car sites and craigslist for Comanches. Depending on condition and 4x4 vs 2x4, most seem to be in the $3k to $10k range, with a few show trucks being much higher in price.