Mike @ roverland is a good mechanic and reasonably priced.
You should take the rig over to him to have him look it over. He can tell you if it's in good shape or not.
parts are not more than any other vechile. There are lots of cross parts too, like GM fuel pumps and power steering boxes... it's all about knowing where to get them. In other words, don't go to the dealer. But again, aftermarket is much more expensive. For example, 4.11 R&P are $400 (for 1 not a set) , vs typcial $150-200.
Despite all this they are super easy to work on. Drop out 3rd like a toy. Axles are weaker than a d44 but with some chromoly shafts and longfields they are just about as strong as toy axles (though d1 axles are only 24 spline and RR are only a 12 spline lol, but you can upgrade 24 spline). Full floaters though on a d1. If you get real hardcore you can retro fit a toy 3rd in and get the full 30 spline axles, but more importantly the R&P options.
It's all relative to how you plan to use it. Anyway, good luck.