to get your "new" purchase to "top" shape?

I got my 1991 560 SEL with 102 K mile in May for $5000. So far, I have spent $1035 on it, including all state paper, inspection, fluids/filters change, A/C charges, ball joint, radio and whole bunch of things. It is very frustrating because it just felt like there is no end to this upkeep thing. The only good part is that I have done most of work myself with kind supports from warm heart folks on this and other forums. I was even able to fix my others cars based on what I learnt here. Had I let dealer do all the works, I am sure it wiould be over $3000 already.

As of today, I am still facing an occasional high idle and a leaky compressor. Pretty soon, I would need timing chain and two new tires. So teh struggle continues.