I am not convinced that you need a new caliper and the price seems extremely high. I replaced one on my BMW with a rebuilt one for $80 but I did the work myself. Your squealing problem is most likely caused by using non-Volvo brake pads. Most of the other pads are much harder and will squeal. You can also minimize squeal by making sure you reinstall the brake shims on the back pads and either use sythetic brake grease between the back of the pads and the calipers or use anti-squeal formulas (which are almost like a gummy glue).