don't think carfax will show the bumper with this one if it had been in a bit of a bump up, carfax only shows things if reported to insurance or the police, if reported to insurance it would have been fixed...presumably....that said, i'd check the backside of bumper for damage and if it's good knock him down a few hundred more and go out and buy and arb or addicted off road bumper or the likes to replace it.
i apply all the same rules to buying a used car regardless of brand,
all of the usual stuff, everything works, no noises, drives and handles well.
beyond that check teh spot where it's parked make sure it's dry, check for seepage at any drive or power train joint, check for signs of rust, check insides of doors,fenders ect ect for over spray and alignment, find all of the vin numbers and make sure they match, check tires for dates and condition, look for uneven paint across the entire car.
mechanically speaking, leak down test and compression test, get someone to drop the trans pan and check for condition, and check fluids in all systems.
so those are the extra things i do not usually listed in most used car buyer guides.
this guide covers most the basics and you can print it out incase you forget a few things, i usually bring it with me as it makes it harder for the salesman to distract me and provides a pretty good visual reference for them when you start beating them up on price as you can show them all of the issues..just know when to stop when haggling and going down the list...
Checklist and Worksheet for Inspecting Used Cars Before You Buy at DMV.org: The DMV Made Simple