Cheaper? I suppose, if you are only comparing the cost of the parts and hardware to an entire trailer.
That’s like saying it’s cheaper to mow 5 acres with a push mower from Walmart vs a large commercial mower. Sure the mower costs only a small fraction but it’ll take you 12 hours a week , every week compared to 2 hours.
It’s awesome that you have the time, skill and tools to do this. I like working in the shop too. Restoring a truck currently, although I really don’t have the free time to do it.
The other consideration is should you want or need to sell the trailer, used cargo trailers retain their value very well, however you’ll have a much more difficult time selling a home made trailer and won’t get as much for it, because no one wants a trailer that they can’t even figure out what brakes and hubs are on it. Add lower residual value to your cost of materials, and unless you’re dumpster diving for the expensive stuff like the aluminum skin, roof, surge brake actuator it may not be much “cheaper” even though you don’t place any value on the cost of your time.
