if youre doing panel replacements on seat covers, I found its cheaper and easier to buy covers straight from Mercedes. Although those years are a little older than the 2013 I did recently.
Some of the Mercedes late model seat covers (E350) are not too expensive from the dealer but I get the solid and perf vinyl from Coast to Coast and just remake the whole cover (reuse the attachment and rear cloth panels) not too hard to do and I make pretty good money on them. I do usually glue some thin foam to the vinyl. The Coast to Coast vinyl seems to be a much better material than the factory MBZ vinyl too!
I agree. The prices on seat bottoms are roughly $250 -$275. I charge $425-$450 material and labor installed. However, for some reason the passenger seat bottoms are really expensive from the dealer. Apparently, they want to sell you the whole seat pan and foam for the passenger side when all you want is the upholstery. So, on the passenger sides, I'll replace panels or reupholstery them to make the job more affordable for the customer.