If you ARE looking for a "used" trailer dolly then CRAIGSLIST OR EBAY IS YOU BEST AND ONLY PLACES TO LOOK.
Craigslist, you NEED to open up your search area by using the NEXT nearest locations listed, then move out a bit further, then further out and so on. It is how I find antique autos and parts.
YES, it is a pain to have to MANUALLY SEARCH CL but that IS the "way it is done" there. Not to mention you are looking for an EXTREMELY expensive doodad that does only ONE JOB that nearly no one is willing to pop for them even used.
So, if you can't find it used on CL or EBAY then it simply is not going to happen.
If you really want one, you most likely WILL have to shell out the money for a NEW ONE.
Personally, those things are not the safest things, most are only designed for FLAT TOWING AND ON PAVEMENT (cement, blacktop), most do not even have any brake control.. Yeah, some folk have bought em, doesn't mean they are a good idea.
Consider having a hitch put on the FRONT of your tow vehicle, allows you to make extremely tight turns and you have the safety of the four wheels of your vehicle plus you could make an extension for the trailer plugin which would allow your vehicle to control the trailer brakes.
