To be honest I overpaid big time for my Explorer but I guess it was worth it. To make a long story short in May of 2004 I bought an '98 Oldsmobile Intrigue from a local dealer for $6000 and promptly blew the engine in it in 3 days (being stupid doing 110 mph on the highway). The dealer said they would take back ONLY if I bought another car from them. The Explorer was just about the only other vehicle on the lot in the price range I was looking for so I had to get it or be out $6k. So I got the Explorer for $9900. But it was in PERFECT shape and had 60k miles on it.
So here we are 5 1/2 years later, my Explorer now has just under 134k miles and at this point I don't regret getting it, even for that price. It has been one of the most reliable vehicles I have ever owned. I have put a little money into it but saved a huge amount because I do 99% of the work myself.
Here's a breakdown of the repairs I've made -
New battery - $90
IAC valve - $60
New inner/outer tie-rods and all 4 ball-joints - $130 (cheap kit on eBay)
Replaced cracked EGR tube - $200
Idler Pulley - $25
The only other $ I've spent on it has been strickly regular maintenance like tranny fluid changes, oil changes, brake jobs, tune-ups, etc. so I don't count those as repairs, all vehicles will need those.
I have put about $2000 into it the for rims, subwoofer, cat-back exhaust, trailer hitch, etc. but obviously those are just for fun.
So all together I've spent about $500 in repairs but I have had it for over 5 1/2 years and put 74k miles on it myself and it is still going strong. My advice to you would be don't pay more than $3000 or so on an Explorer unless it's a newer 98-01 lower mileage one, and make sure you get the V8, much more reliable and gets close to the same gas mileage as the V6's. Also when something goes wrong fix it yourself, these Explorers are pretty simple to work on so there shouldn't be much you can't fix yourself without a little research.