Try E-Bay, search "Mercedes repair manual".
I got mine for 28 USD from a seller "pcgate", they are selling all kinds of repair manuals for MBs.
99 BMW 540i 6-speed 110K Km
03 SAAB 9-5 wagon 80K Km
92 400E (Sold) 245K km
Still missing the days with the Benz, it kept me busy.