I have a Haynes manual -- and I find it to be quite good. My car is a 1992 190E/2.3, and the manual says it's only for 84-88 190E/2.3. I bought it out of desperation because I couldn't find the right one -- but I haven't found anything yet that's NOT appicable to my car. In my humble opinion, well worth the $10-$15. You can get them at almost any parts store. (Napa/Pep Boys/Advance)
You might also want to check out this forum:
It's exclusively for 190 enthusiasts, and someone there was selling copies of the MB CD Manual (for about $20 bucks I think).