I built my own, but I did notice these a while back. The price isn't really that high when you look at the materials he used.... He is mainly pitching his bumpers to those folks that need a good bumper but don't want to spend the $600+ for a welder, $200+ for a chop saw, $75-100 in materials, $35 for Argon/CO2 mix, $ for electricity to run all these..so when you look at it that way, those of us that that do have our own welder etc actually paid quite a bit for our bumpers...LOL. Now I know over time that my welder had more than paid for itself, but it takes time and a little $$ to keep it running... So $375 ready to go without any labor is not to bad....
I am not promoting these at all, just wanted to point out his reasoning is probably pretty sound.
My .02