Ridiculous prices.

If you can manage the R&R, send it to Sun Valley in CA. If they don't have an exchange, they can do your transmission.

https://www.mercedesdismantlers.com/Mercedes%20Transmission%20Price%20List.htm

I use a very experienced shop in New Jersey. They can rebuild your transmission and are priced well. They also do a lot of work for dealers. Call before you order online:

https://autotransparts.com/cart.php?m=product_list&c=496
TRANS SPECIALTIES | Remanufactured transmissions | rebuilt transmissions | transmission parts | torque converters

When you do this job, also do the rear main engine seal and the driveshaft flex disk. The parts cost a hundred bucks. If you install them now, it's no extra cost. If you do them later, installation cost alone will be $1000.