Keep any eye out on your local craigslist or check some of the facebook pages for a trailer. I've seen some pretty good deals on open trailers.
I wouldn't go less than 14'. I liked my 16' as it was enough room for the car and carry some extras. Also good if you are using to haul other vehicles or things.
Before Christmas, someone decided they needed my trailer worse than I did. Yes, Stolen! Be sure to secure your trailer when it's not in use.
If you by chance you find a really good deal on a black 16' open flatbed trailer, 2x6 wood decked, tandem axle, electric brakes, aluminum tool box mounted on the front, silver painted wheels with purple painted hubs, no fenders and a permanent Montana license plate; I just may have the title and 2 spare wheels for it.
Steve