When I pick up my Tesla I am considering asking to purchase a spare UMC to keep in the car. I will leave the one I get with the car permanently in my garage connected to a 6-50 socket (already have the UMC 6-50 adapter). So I only need the UMC no adapters or zip case. I think I read on one thread that the sell the UMC only for $480. Has anyone done this?