poor relative said...
Cheap as in 6-800
Good working order as in Lights work, no holes, Axle springs and bearings are not problematic
Boxy as in 90 deg boxy
I thought you meant a cheap one, not a good one! 6-800 gets you a pretty good trailer.
Last I looked, the manufacturers like John Papas had a lot of customers who trade in for a new one every year or two, so they refurbish the trade-ins and sell them at about your price range. Prolly still a rip off compared to private sale though.
Better option is to get a lic 6x4 with rusted out floor and fix it. If so PM me, it is easy and there a few tricks that will save you a lot of time and $$$ when replacing floors.