How to implement a BLDC for variable torque in its phase (InstaSPIN, TI)
It's been a while so I'm not sure if you're still interested but.. there's a couple instaspin kits that fall under $100 total. It just depends on your motor requirements.

At the bottom of this page, there's a list of kits:

I've used a launchpad board (F28069M) with the BOOSTXL DRV8301 to drive a hefty air drone motor (20A+) at 15krpm. Just a note, drone BLDC motors tend to have very low inductance so you might want to look into the motors' spec.'s beforehand. The low inductance makes it difficult for instaspin to track the motor. Also, the control's also limits the motor speed. These very fast motors 15k+ rpm can be tricky for the limit microprocessor speed available. TI's community's pretty active and I'd definitely recommend looking and asking there.