Then look at the work Paul has done to control the Nissan Leaf motor. He sells boards to drive AC and DC motors. You would have to buy the 3 IGBT half bridges needed to get the power to the motor also. But that should be a lot less expensive in total than the $8k for an inverter you quoted.
Here is the driver board:
https://pandspowerelectronics.ecwid.com ... y=22093524
And the resolver to encoder board:
https://pandspowerelectronics.ecwid.com ... y=16287307
Here's a video showing Paul controlling the Nissan Leaf motor: