You can get springs from a lot of places... Caliber, Buds, Millers, and from various members of the forum. Performance spring kits are also available so shop around.
Front spring removal is detailed on page 187 (figure 11.13) and rear spring removal is on page 194 (figure 11.45)of the Haynes manual. If you want more detail go to Job 32-4 and job 32-5 in the Mercedes-Benz service manual (for cars starting August 1959) or Job 32-5 and 32-6 in the 68 to 72 manual. You do not need a spring compressor
With a floor jack and jack stands in my garage it takes me about 1 hour to R&R the rear springs and about an hour and a half to to R&R the front springs. I have a friend who just bought new springs from Gernold and says I am a little slow.
Do it yourself and you will save $2100 and 19 hours to do a lot of other things to your car.
Tom Hughes
St. Louis