I think you over-priced it a bit....
I had made quite a few for members and tech friends over the years , and some are still being used...but I never sold any.
Doubt you will get $50 for one, though you never know . if one can get $30 for a 19 cent resistor for aux fan, guess one can get $50 for a 49 cent diode..
good luck to ya .. I like the spirit of it ..
Want a simple OBD11 other one to try ??