I'm not sure where you are looking but I believe there are a lot of nice lower mileage trucks for under $15k....I have owned a few, and they are not hard to find.
If you are looking at car dealers, you are looking at the premium prices. I almost always look to private sellers for the better deals. The same truck you might find at a dealership would be several thousand $$$ cheaper from a private owner....at least most of the time.
Not being a car guy, you would certainly want to have a vehicle inspected by a legitimate mechanic BEFORE a final purchase.....good luck