Ive always loved the Supra but hated the OEM shifter. The aftermarket options are very overpriced and I don't think that they addressed the real issue with it. So we have been playing with different design options off and on for a couple of years and finally have something that works really well.
I started from ground zero with all of this and like you got quotes that where all over the place for the CNC work involved. Xometry has hands down been the easiest option for me on getting this done. Their prototyping is a little expensive but any type of bulk run order seems very competitively priced. Also if you call and ask they will usually give you 10% off on prototype runs.