Q: Power windows failed after seldom being opened

The power windows in my car have failed. Something stronger than the plastic guide needs to be used; the plastic guide just is not strong enough. Also, I know that just the guides can not be replaced since Buick has them moulded to the regulator arm. The whole thing must be replaced, even if there is no failure in the regulator. I had a mechanic to tell me that it is a design flaw. The passenger window was the first to go, then the rear driver’s-side window broke and then the driver’s window. The driver’s window had been opened less than 10 times and the rear window less then 5. Hundreds of dollars per window. Since my car is no longer manufactured, is that why windows are more expensive than I’ve heard of the price of newer models’ windows?