On my 16v it was the inner LCA bushing that was causing the creaking, as seems to be the case with yours. I did this (mostly) myself, and it was a major pain it the buttocks. There was no way with the tools I had to extract/beat out etc. the bushing. Apparently there is a special tool just for this, although it is like $500 so not practical unless you have a fleet of 190e's. What I ended up doin was taking the whole lower control arm off ( 4 bolts basicly) and taking it to a shop to have them change the bushing. They tried pressing it out with a 20 ton press but it didnt budge. Then they melted all the rubber away with an acetalene torch and knocked the rest out with an air chisle, so you can practicly forget getting it out while its on the car. Then they pressed the new one in. This cost me $20 so quite a bit cheaper for you than the $250. On the rear spring you dont have to use any type of compressor. After the car is jacked up the spring is basicly loose. I had the car on stands and put the jack under th LCA, it came down like an inch until the spring had no tension at all on it, so its safe. You have the bolt for the inner bushing, the outer one, the sway bar, and the shock, fairly straight forward. It takes under an hour to get it out and same to get it back in. I was so relieved with the loud creak gone
Good luck!!!