air conditioning question

I took my car to an independent garage who replaced the serpentine belt on v6 altima. After 10,000 miles I would get what would sound like the belt sqeeking when ever I turned on the ac. I took it back to the same garage and the mechanic told me that it was not the belt but was the ac compressor. They went on and gave me a quote for 1,700.00 to fix the problem. They said not only do they need to replace the compressor but also many other components on the ac system due to the possibilty that metal shavings from the compressor might have gotten into these other parts, and this was the only way that I can have the compressor under warranty. The car has 100,000 miles on it and I am surprised that this happened so soon. Are these guys trying to pull a fast one on me. Any suggestions would be appreciated because I like the car but not that much to put that type of money into it. Thanks