Suspension Troubles

I bought some lowering coilovers for my 2000 Saturn SL2 and installed them.
When installing them, I noticed I was in need of new struts. I work at an
automotive supplier, so I bought some new Monroe-matics for cheap with my
discount. However, I noticed the rear struts were making squeaking noises.
I have replaced (on warranty) the left rear one twice, and the right rear
three times. I even raised the coilover to release some stress from the
strut, and have had no luck. I took it to a mechanic and he wanted to
charge me $100 to do what I have done myself multiple times, for free. I
have given up on simply changing the strut. If any one has a tip or trick
for me it would be greatly appreciated.