Mark,
Nothing wrong with buying one already done.
Some of us like building, some like camping, and some like both!
If you really prefer to keep your garage for the car and other things, you should pass on a wood trailer.
Sunlight as well as wet weather will trash the finish pretty fast (think sand and revarnish 1-2 times a year).
And that isn't counting what happens if the finish fails, or a seam opens up un noticed (think complete loss).
Hail, tree branches, and other outdoor hazards are a lot harder on wood than aluminum, properly backed.
If it is just the look you are after, the new vinyl graphics might be an okay substitute?
I have a wood bodied trailer. Looks nice, but is a lot of extra work and sometimes worry.
If you just want to go on carefree trips, choose a style/exterior that will stand up and be easy to care for.
If you live and camp in the Colorado/Utah/Wyoming area, a hard exterior surface will hold up better to gravel/rock roads, sand, etc.
Insulation in the ceiling helps a lot, in the sidewalls helps too, but not as much.
Rob
Waiting for "someday" will leave you on your deathbed wondering why you didn't just rearrange your priorities and enjoy the time you had, instead of waiting for a "better" time to come along...