You could also try salvage yards for seats but condition might be a factor. I have seen plenty of used seats on ebay for various models, and those too might be options.
Though the only reason i look for seas for 126 or 124 chassis or newer benzes is to make a new computer chair for my desk.
'92 300CE - Sold
2004 C240 - C7 Wheels
2015 ML350 - P1, Pano, Ash poplar wood, Sport Dinamica interior, Running Boards Keyless go.