The balance of Price/Quality and customization is a tricky one.
It doesn't seem possible (or realistic) to expect a custom builder to compete with someone like Winnebago, or even Roadtrek.
Sportsmobile tries to be somewhere in the middle.. I owned a Sportsmobile (which I bought used) and it held up really well, though they are not exactly cutting edge when it comes to design and current trends, but you can select from allot of "custom" (prefabbed) pieces they will try to combine and arrange to your liking. They do seem premium priced when compared to "assembly line" models.
On the other hand, I think they are pretty competitive if compared to a completely custom rig. I think you can get a nice complete rig for less than $100,000..
Transit, I think there are a couple custom builders up in your neck of the woods, Outside Van comes to mind; they recently sold a Promaster "upfit" for $59,600 which looked pretty sweet! Next Mission - Outside Van
(It WAS missing a few things; like power, water, bath, toilet, sink, furniture, solar, screens, windows, TV, radio, dvd, a/c, heat, lp, generator, etc...
) but it was sweet.