They did the work - backs and bottoms.
I've asked Upholstery Tech if they'd do seat heaters for example and he would install the pads but not do the electrical. I'm sure he could do just the install if you'd want to source the skins yourself.
Yig's off of Power Inn did mine originally for $300 but they are out of business after he passed away. I've had Upholstery Tech in Elk Grove do other seats and are reasonable.