Convert your garbage Bendix calipers to Girling. I did it, and once I did, there were no more problems with binding or excessive pad wear or anything. I never realised how GOOD Volvo brakes were until I did it. You'll have to have the 2-piece hub and rotor set up to do it(most cars have been converted but I don't know what year yours is), and make sure you buy the right rotors and all, but once it's done you'll be very happy with the results.
As for where to buy parts, you should be alright with just about anyone who sells remanufactured calipers. You might want to look at fcp groton (foreigncarpartsonline.com) or gapa(gapa.com) to save a few dollars. Many times you can get a good deal on a pad and rotor set from eBay- I did. My calipers came from Imported car parts of Poroco here in New Hartford, CT. No core charge since I'm such a regular there, so I got 2 remanufactured calipers for about $180 out the door. He just said to make sure I brought back the old ones.
Oh- you may want to replace your brake lines while the calipers are disconnected, too. They tend to get weaker over time, and since you're gonna be down there anyways, you might as well. I was forced to do it when I did the brakes because I snapped some of the lines trying to get the job done quickly(it was February). Be sure to have plenty of brake fluid on hand for when you're all done. Flush the system out, and see what Volvo brakes are supposed to be all about! Good luck and all that fun stuff.
...as an alternative, you could always go to midas or something and get their "lifetime brakes" -they suck, but once they're on, they replace them whenever you need it. And having someone else do it is much less labor-intensive than doing it yourself...
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1985 245 205k and counting. Charter member of the Martha Stewart Racing Team- "It's a good thing"