I just bought a 2008 6.4 truck with around the same mileage for 2500$, it's a 4x4 xlt nice truck, interior really mint after cleaning, front end all redone.
I bought mine with the front harmonic damper and rear flex plate all mangled, but I am putting another engine in it, (non 6.4) so it doesn't matter.

You could find a truck with a blown engine, and there are places that have 7500$ long block engines with 100,000 mile 5 year warranties to go with them.

Then sell the parts off the block thats in there, make some cash back off it.

 

Around my area a truck with 250K miles sold for $7000 with engine problems. 08 King Ranch F350 SRW. It's hit and miss with these trucks because regular maintenance and how it was used previous affects longevity. I have an 08 F350 I bought with 250K miles and have had very little issues with it now creeping up on 300K miles. I have a buddy with an 08 F450 King Ranch with 106K miles that needed a hpfp and a year later blew the turbos plus one piston resulting in an engine replacement.

Like mentioned before, gotta go with your gut. If possible, check the engine hours. My f350 has 296K miles and 8200 hrs.