I've got a couple extra sets of these...do you have your own skins for them or do you have a specific color you are looking for? I have passable pairs in bamboo and parchment (both real leather). One of the other parchment ones I have shrivelled up from the sun and should probably have the foam pad replaced (compatible with the front headrests). The blue pair is a clearly aftermarket reskinning. The skins are the same as for front headrests, so they can either be pulled from extra front seat headrests you've found or obtained new from places like GAHH or World Upholstery.
http://gallery.w116.org/dl/37848-4/31.JPG
$150 for a set complete with mounting hardware (I can provide more photos if you're interested).
P.S. If you haven't already, check out w116.org - it's a fantastic resource for these cars!