How actually inexpensive the Leather "Kits" are...to Mercedes.
(Would you believe less than $500.00,includes door panels,Etc. ?)
DK Switzer makes a large portion of them.
BUT,Just like Home HVAC and Automotive Alternators/Generators and Starters
the "Industry" has the Supply "Locked Up".
I.E. :
http://www.mbclub.co.uk/forums/interior/73087-leather-interior-kits.html