500e Ppi

[tom woolner]

I just got the PPI back on a 92 500E w/ 96000 miles. Power steering pump leaks, a/c is cool, not cold, and one of the nitrogen cells in the rear needs to be replaced. Also, variousw minor leaks, including weeping at the valve cover gaskets. Their overall opinion is "excellent" for the year and mileage.
My question is; how much are the parts for replacing the nitrogen cell and how much labor is involved (I will have a shop do the work). What's the chance that the a/c problem may just be a minor leak, requiring freon? Should I spend the extra money for an a/c diagnosis?
The car is reasonably priced, and a 2-year (not Starmark) warranty is available. However, it is quite some distance and will cost $1500 to ship.
TIA
Tom