I have a big enclosed glider trailer that may fit the bill.
It is home-built by the guy before me, and is quite reasonable,
really.

Tows well, light-ish weight. Aluminum. Skin-on-frames type
construction.
New trailer tires w/ about 300 miles total on them. (Nearly $250 in
rubber.)

I would let it go for $500. It, honestly, is in my neighbor's driveway
b/c I don't have a place for it.
Yes, I am THAT neighbor.
If you want a pic, send an email address and I will get some dims and
pics back to you.
May be a good match: Big, roomy, not expensive.
I will be advertising soon. Like tomorrow. I need to move it soon.
~Travis
North of Seattle about a half hour.