Pontiac Repair: 99 Grand Am A/C, manifold gaskets, liter engine

Question
1999 Grand Am GT - A/C and heating levels 1 and 2 don't work at all.  3 through 5 work just fine.  The force of the A/C varies from day to day.  Is this an easy fix or should I have it done?  What could be the cause?

History: Worked fine up until about 70,000 miles - recently had brake work done, new battery, new alternator, coolant reservoir leaks (i'll repair soon), and there is an oil leak that was brought to my attention recently.  Mechanic says both sets of gaskets are worn and parts and labor are approx: $450 for the oil problem alone.  Does that sound reasonable?

Answer
For the 1st problem, I assume that you mean that the blower isn't working on the first 2 speeds. If that is the case, you need a blower resistor. Its located under the dash in front of the blower motor.
For 2nd problem, You didnt tell me what engine you have or what the tech said was causing the leak. I assume that you have either a 3.1 or 3.4 liter engine and that the lower intake manifold gaskets are leaking. If so, yes the price is about average.