Brought my adapter plate template to a machinist I know this afternoon, and got a price of $60-70 CDN for 1/2 inch aluminum plate to make it (we make it).
Edit just looked up prices for a pre-made GEO adapter plate: $145 US + shipping
here
Also talked shaft coupler ideas. This guy will likely be involved in helping us mate the electric motor to the tranny, due to the non-standard motor shaft issue (it being internally splined, as pump motors are, apparently).