I think you should do some research into what brand of trailer you actually want, and what size will fit your usage. They all have some compromise that you either can live with, or not. Bigfoot's are big. They are more expensive to tow, but more comfortable when you get there. Trilliums have a fibreglass interior and floor. They typically do not require gutting, but are kinda expensive compared to other brands. Bolers are less expensive, but seem to need a new floor more often..... There are so many.
I agree with Mike & Sara. If you plan to gut and restore, don't pay too much. About $1500 for a trailer that need that much work is the most I would pay.
The things you should confirm are OK, or easily fixable are as follows in order of importance, (to me):
Fibreglass shell - Small holes, or punctures are OK, but if it looks like there has been heavy erosion or deformation, just walk away.
- Are they a style you like? Do they work? Do enough of them open? Can you get replacements, parts?
Floor - This is the most likely problem area. If the trailer has been leaking for some time the floor, if wood, may have rot. Depending on the model of the trailer, this could mean an off frame restore, not just gutting. Look for soft spots in the floor.
Frame - This is actually less of a problem if you can weld, but if the frame has to be replaced, it can get expensive.
Appliances - Do you want a furnace
, gravity, or forced air? Ice box, or fridge
, 12 VDC compressor, or propane
, does it work? Stove, does it work? You can expect to need a new propane
Smell - If you are gutting, not so much of a concern.
Those are the big ones to me.