Keep watching RV trader, many dealers list there. I watch for Traverses, some days there might be two or three in the whole country, sometimes none, sometimes a half dozen or more.
Not many were made. For several years, the whole B market was not much more than a few thousand units a year.
Another option is to connect with a used vehicle dealer (there are conversion van specialists on many metro areas) tell him what you want, they can find the units when they are still wholesale, pick up at auction for an assured customer. These, and some categories of travel trailers, as well as specialized motorcoaches, fall into that part of the market where most dealers don't buy them for stock. Kind of like classic cars.
If you want new, Sportmobile can build you something much like the Traverse, but no longer on the E150, since the van is no longer built. Unless you bring your own van. They can build it on a higher payload van too.
Tom Test
Itasca Spirit 29B