From the what it's worth dept:
I ordered a pair from calipersonline about a year ago and they were very prompt to credit my credit card when I sent in the old calipers. They're working great and I recommended them then and now.
I just read Dick's comments as advice of caution which is always good advice when doing anything online.
I don't know how many they have but at the time I had placed an order from another source only to be shipped the RH side without informing me that the LH side was not available. I didn't want to tear down the LH side and wait up to six weeks for them to rebuild.