Common rust worm places are rear crossmember, and all out riggers, especially the front ones. give them all a prod with a screwdriver.
check the fuel tank isn't leaking, especially if it's been off road.
Check difflock works (& light comes on)
All above are resonably easy fixes for a competant DIY mechanic/welder, but for the price that you're paying, you shouldn't have to be doing any of them.