Jeep Cherokee.
Can be had for way under 10k, very reliable 4.0 is a straight 6, finding one under 100k will be a problem but the engine is known to hit 300k there a couple guys on the jeep forum I am on that have over 400k. 99+ models did have some head cracking problems but also have the better intake manifold. If you want to mod it the sky is the limit. The only bad thing about it is gas mileage except low 20s on the highway and teens in city driving.