With this crowd, expect 'a jeep' as an answer. LOL
With 4 grand you get a good solid jeep as an starting foundation. I would say a good early model wrangler 97 and up could be had , since the JKs are all the rage now. A quick trip over to JP magazine's web site you can find an article named steal J, about finding a low cost tj 97-06 that hasn't been beaten to death. Since you live in the snow belt I would take a careful look at what ever you buy since jeeps are a rust magnet. For that same reason I would be leery of older Cherokee's. But I am a wrangler owner and a bit biased. A TJ is a good platform for a new time jeep owner and there is lots of upgrades available to this platform, compared to a YJ or earlier CJ's. But this is also depending on how good with a wrench you are. Some like the challenges of an earlier model compared to the newer electronically controlled newer models. The internet is a good source for information about each year/ model of jeep out there and what to look for about the problems each year had. And asking questions here. You found a good site with lots of friendly people who are willing to share their jeep love (addiction) with new timers.
Feel free to ask as many of questions you have, we are here to help.
Once again welcome to group therapy (jeepz board), LOL