Don't have a pic readily available, but I have a 20' Interstate trailer. I bought it used for $3K cash, but new they are around $7K I think. Best bang for the buck IMO as at that price it has dual roof vents, lights, D-rings, finished walls + floor + roof, big side door and so forth.
I wanted an enclosed trailer for a few years and found that deal too good to turn down. It was hardly used (the guy used it mostly for additional storage of his Chevelle project!) and he bought a big-arse baja truck and needed an open trailer for about $3K
I would buy a trailer used and not new. Funny thing about them is they seem to not decrease in value that bad, but they decrease to a point and then don't seem to go any lower (unless you F it up or let it rot of course) and there really isn't much to wear out. So I bought mine used at a point I could probably sell it for a few years from now should I win the lottery and need a FeatherLite hahaha.
I find the 20' to be perfect for our cars as well. Plenty of room in the front to get in and out of the side door for loading/unloading, I have my whole rolling tool box in the front at the track, etc. I thought about a shorter trailer but am glad I found a 20' at a good price. Longer is just more weight and typically the torsion bars in a 20' and 24' are the same, so you have less load capability with the bigger trailer if you can believe that, so you end up hauling around empty dead weight IMO.