Avclay,
I just bought a used, 14' X 6' 8" W X 18" deep, low profile dump trialer. It is 14,000 gvw, has brakes on both axles. This trailer is a 2001, built by Sands Welding out of Michigan. It was owned by a masonary contractor, and had been well used when I bought it. I had to do some welding repairs, straighten fenders, repair/replace lights and wiring, and, I ended up repainting it cause it had mortor splashed all over it. Also had to replace some of the bearings/races on the axles. I paid $2,000.00 for the trailer, and after all the repairs, have about $2,500.00 in it.
I had looked at both used and new dump trailers for about a year before I found this one. I have a JD 4310 with loader and backhoe that I haul in this trailer. My truck is a Ford 2003, F 350, short bed, 4X4, dually.
Some observations/opinions based on my experiances so far.
If your going to haul a C.U.T. in a dump trailer, you need at least a 14' bed. I have to drop the bucket off the loader arms to fit mine inside the bed/tailgate, with a 6' boxblade attached to the 3pt. Bucket sets on the floor in front of the tractor and loader arms set on top of the front of the trailer box.
You want to look at the type of lift that the trailer comes with. Mine is a scissor lift, and seems to work fine, but I think a double cylinder would be more stable and lift better. You also want to have grease zerks on all the pivot points on the lift and trailer. A lot of the cheaper trailers don't have these. My factory trailer hitch on the truck is rated at 10K pull/ 1000 lb. tongue - with a weight distributing hitch. In order for you to use a tag trailer you will either have to change your factory hitch to a heavier rated one, or, install a W.D. assembly on the trailer. None of the ones I looked at came with the W.D. set up, and all of them had a straight tongue, so installing a W.D. set up takes an adapter.
I have hauled 10K lbs. of recycled roadbase in mine, with out any W.D. hitch, and it really is important to have it loaded so you don't have too much tongue weight. I hauled seven loads like this, but only 3 miles total distance. If I was to go farther, I would install my W.D. setup off my car trailer before attempting it. Even with the one ton dually, it really gets squirley.
You also want the trailer to have heavy duty tie down rings, or install them yourself, to tie down your tractor. Under bed storage for the ramps is also a big feature. My ramps store in a cradel on the front of the trailer box, and are a real pain to have to haul out and around to the back every time I want to load/unload. I will make storage hangers under the back of the trailer this summer to fix this.
Look at your tailgate options also. Mine has a three way tailgate. Spreader, opens at bottom with chains set to the size gap you want for spreading gravel etc., Fold down, like a pick up truck tailgate, and right side hinge, swings around to the side for loading/unloading equipment, or dumping trash.
You will also want either a corded remote switch for the hoist control, or, some of the builders offer a wireless remote. It is real nice to be able to raise the bed while still in the cab of the truck to spread materials. Also nice not to have to stand right next to the trailer when dumping. Mine has a single lever on the front of the hoist box, so I have to be right in front of the trailer to run the hoist up and down, not very convenient.
Looking around, you'll find these trailers run from a low of about $4,700.00 to over $8,000.00 depending on brand and features. Around here, they seem to maintain their value pretty well. I think for what I spent on mine, if I keep it in decent shape, I can use it for 3 or 4 years, and sell it for as much or more, than I spent on it.
One other thing, I bought a tag trailer cause I have a shell on the back of my truck, and carry tools all of the time. A goose neck would be a better overall dump/equipment traler cause they tow better, carry more weight, are available in longer/wider dimensions, and are more manuverable. But for my occaisonal use, a tag works just fine.
Hope my ramblings help, or at least give you some things to think about.
Good luck with your search.
DT