Welcome to the board and welcome to the obsession Hunter. Is there a reason that you want specifically a 71-75? What are you looking to do with the rig, daily driver, crawler, mudder, show? Where are ya located too because that will effect the price of the rig. I have a 70 that I would like to get rid of, but it needs work...it is something you can definatly call a builder project, but it does run, and runs strong.
As to what to look for, look for any rust (floor pans, inner fender aprons in the engine box, under the rockers, along the body seams, tailgate, etc.) and any modifications. Make note of what they have done to the rig and if you have someone to help you look at it, take them along. If you don't, take a camera and take some pix and load them up here and we can help you out. If you are looking for something that is completely rust free that is roughly running, just needs some TLC to get going, you can expect to pay a premium (8-10k range) if it is a moderate project builder that is in decent condition, moderate rust look in the mid range (4-7k) and a complete project that needs panels replaced, engine work maybe tranny work look for those in the low end range (500-3k).
It all depends on what you want to spend and what you are capable of doing. These old rigs are easy to work on and that makes them great for first time gearheads (if that is what you are). Otherwise, you can go from mild to wild on the modification scale. About the only "original" parts on my 72 daily driver are the transfer case, body, front axle & engine block. The rest has either been replaced or upgraded at some point in time.

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Hope that helps you out some, if you are interested about my 70, shoot me a pm and I can give you some info.