The CDs from MB have never been as comprehensive as the actual service manuals. For instance, I ordered the 126 CD set from MB and looked for the procedure on how to remove the transmission. I could not find it anywhere so I called MB and they told me that is a dealer operation and beyond the scope of the CDs they sell to the public. I was extremely pissed to say the least!
I have since acquired a complete microfiche set that pretty much has everything from the end of WWII until about October 1991 - about 375 sheets. Dealers used to use them until they went to computers. They show up on EBay occasionally and are worth quite a bit. I recently saw a set passed over with a starting bid of $399. I got mine for about $30.
Somewhere in-between is more than reasonable. Cheap microfiche readers are also available from Ebay or maybe your local library has upgraded and is ready to chuck out an old one.