You can always try Craigslist! My dad got his at a flea market for $5.
Granted, its a slightly worn child trailer, but it will still haul things just fine, it's just not as pretty as a new one. If you don't like the canopy or its too worn, you can trade it for a plywood floor or make a new cover.
I rarely have cause to use mine, and I would not get rid of it for anything- its so handy to have. Eventually I might get to transport my niece in it (thats if I don't get her on her own Strider-type bike first!), or my dogs (they're learning).
Good luck with both the search for a trailer and your move. Roommates can be a hassle or a ton of fun.