Where?

Here they have it listed for 97 bucks

http://www.importecwarehouse.com/Mercedes-Wiper-Motor-W124-124-Bosch-System-87-95-p/mb1248200708.htm

Oreilly auto has a reman for 115 lifetime warranty

http://www.oreillyauto.com/site/c/detail/A1C0/431513.oap?year=1987&make=Mercedes-Benz&model=300D&vi=1430267&keyword=wiper+motor&pt=03292&ppt=C0047

Auto parts warehouse Bosch OE, 107.00 free shipping.

http://www.***********************/details/QQMercedes_BenzQQ300DQQBoschQQWiper_MotorQQ19871993QQW0133-1603823.html