What everyone who's modifying a truck (or medium ambulance) needs to find is a local, independent repair shop. Freightliner touched my truck ONCE, and I'm still whimpering about their prices. I found a local place just a few miles away that I use when I run into something that I just can't handle myself, and they have found that when my truck is in the shop, I show up with a couple dozen donuts.Tri-Van truck body is near me in Ferndale, WA - they do a lot of custom builds for all sorts of industry (ambo's, service trucks, hot-shot crew transports etc). I took a tour of their facility as part of a project I'm proposing at work - it's a full service facility and they do really nice work.
that said, while mine isn't a budget build, i'm hoping to avoid needing a shop for anything since labor is a huge expense