At that price point, you're going to be looking at older trucks, likely with fairly high to high mileage. So, how well an individual vehicle has been maintained is going to matter more than brand or model. 

My advice would be to look at trucks in your area, then start eliminating the obvious bad choices (vehicles that have been in an accident, vehicles with a high number of previous owners, etc.). 

Once you've whittled the list down to a few prospects, have a good mechanic inspect the vehicle(s) before you buy.  Trucks in this category might need a little TLC to be completely sorted or to be good to go for the long haul, so I'd recommend doing a little research into parts and repair costs, too.