Here is a great link [url]
http://www.trailershopper.com/ [url] I wanted a trailer built and this is where I found the most info about trailers and cost for each thing I wanted, I went with a 7x7x16 I think if I were to do it again I would go to 18 or 20ft but I still like the size and 2 axles is the way to go, I park my golf cart over the axels and it tows perfectly if it's to far back it pulls ok but sways some.
I think it's worth the money to have a RV door with screen and windows installed from the factory, if I were doing it again I would have them also install a cut out for a window AC and I would have a generator door installed on both sides of the front v nose so I could run the generator from inside without having to drag it out and run drop cords.
I also would like to have a better bathroom with a RV toilet and holding tanks,I am in a situation now where I can leave my trailer at a gun club for as long as I want and with a portable toilet I have to manually hand dump it.
I would also get the stabilizer jacks installed from the factory they were well worth the 50.00,