Should I just DIY it?

I'm looking for a mobile kitchen for my catering business. A trailer with concession windows that I can do festivals or whatever out of. So I've done my homework, shopped around n got quotes, I'm so over this decision of weather to buy new, buy new and get beat , buy used and have to fix/ customize someone else's vision to fit my own, or buy a shell and build it myself with my own vision, a couple of skilled friends, and payments in beer and mucho favors. I have my kitchen laid out to my specs in my garage and have been talking to a few companies about a new build. I know what I want and have a good idea on what I'm looking for but it seems all my questions seem to bug the builder. Any idea what I should do?