there is a shop manual on ebay now for $50. There are many others too. You specified hard copy-- but if you can use the cd version there are some manufacturers manual collections for $17.
other links to get you started:
http://books4cars.com/result3.htm?finddesc=123&Submit=Go
http://stores.ebay.com/Chriss-General-Store_W0QQsspagenameZl2QQtZkm
directly to the ebay site:
http://motors.listings.ebay.com/Car-Truck_Mercedes_W0QQfromZR11QQgotopageZ2QQlopgZ2QQsacategoryZ34227QQsatitleZQQsocmdZListingItemListQQ socolumnlayoutZ3QQsocomparecolumnlayoutZ1QQsocurpageZ18QQsorecordsperpageZ50QQsosortorderZ2QQsosortp ropertyZ2

darkman
1987 300D Turbo 191,100