An afterthought...
When we were shopping, all the options for purchasing a mod home were thru a general contractor. The home manufacturers had specific GC's in each region of their delivery territory. One had to purchase their home thru the GC for that specific area. The GC would then contract the required sub's to bring it all together. My contract to purchase was with the GC. We started with about a dozen different manufacturers, then 3, then whittled it down to 2. We then lit both ends of the candle and played them against each other.
I do recall, though, that one of the 3 last players was a different approach to mod homes: Design Homes. They DID work directly with the purchaser. There was no middle man. As I recall, they did everything except the foundation. To this day, I believe they still operate the same. Kinda fun to shop and look for clearance bargains.
Design Homes