It sounds like the three that were linked earlier were in pretty rough shape. The low number of photos on all of the ads leads me to believe that their interiors are all trashed and/or the owners aren't trying very hard/don't know how to sell them. For example, not a single one of those vehicles were washed prior to being photographed and the lighting blows in every photo. The sellers can't expect to get top dollar if they aren't going to market the vehicles accordingly.
Option #1: Take your time and be willing to drive 500+ miles to check out other rigs as they are posted on Craigslist. You'll make a couple road trips to check out vehicles that will end up being garbage but maybe there's some cool parks you can check out on the way making the trip worth it. I know that being in Chicago makes finding a decent one tough (I'm originally from there so I know how bad the rust can be).
Option #2: If you don't want to wait, I'd throw a really low offer on one of the three that were linked from Craigslist. Offer $1500 cash and you'll come over right now to pick it up. Sometimes people just want the leaking hunk of metal out of their driveway so it stops leaving oil stains. The advantage of this is that (i) you'll have enough money left over to fix whatever is necessary to get the thing reliable, (ii) if you dent a door or damage something you aren't terribly upset because it was cheap, and (iii) you'll learn A LOT about the vehicle doing all of the maintenance making you more prepared on your next overland trip.
If you're not very mechanically inclined, this could be a good project for you to learn more and practice. Somewhere (maybe it was in the vehicle builds forum?) there was a guy who picked up an old Land Rover for ~$1800 and then used the savings to start doing maintenance and upgrades. If something were to happen to my Jeep, this is the route I'd probably go - find something fun for dirt cheap and then start doing all the maintenance and upgrades myself so that I am very familiar with the vehicle. While I love my Jeep, I'm not terribly brand loyal and, in this scenario, I'd consider almost anything under the sun to fit the bill (e.g. Toyota, Lexus, Jeep, Land Rover, Mercedes ML, etc.).