I bought my truck via a small dealer, but it was close to 200k and previously used by big construction company.
After vacuuming and washing couple HUNDREDS of Arizona dust from it and patching few small issues, the truck turns extremely reliable and performing from what I hear way above average.
Part of that might be luck, part that big companies service the truck regurally -even when employees abuse them.

 

I just paid 5700 for my 02 F350 dually reg cab 4x4 w/180k. Has XL interior just like that one except mine has cruise. I think you could get that for 3500 or so.