Fortunately, early ths year I was able to score a 4-book set of W123 factory repair manuals off Craigslist for $75. I have some Haynes manuals for other makes, only because my local Fairfax County library system decided it would be a great shelf-space saving idea to discard all their Mitchell auto repair manuals.
I find the Haynes manuals to be pretty crappy, with much info on changing parts, but limited diagnostics, and lots of frustrating lawsuit-inspired references to the 'home mechanic', as in "Because the complexity of this repair is beyond the scope of the home mechanic, we recommend taking the vehicle to a professional repair shop."

Happy Motoring, Mark

__________________
DrDKW