I have these exact seats (power/lumbar/heat/inflatable bolsters) and they popped up on a prayer.
There is a guy on Fanatics that parts out M3s all day long... I believe he is in California.
Thanks for the heads up, I'll keep my eyes peeled for that seller (I've been checking daily now over there). How much did you pay for your set, if you don't mind my asking? Were they local?