For years we replaced calipers as they were so cheap. About ten years ago they doubled in price and have been going up ever since. We now rebuild all calipers that are leaking and are rebuildable.
In looking at the parts, I noticed that the Bendix Calipers are about a hundred dollars cheaper per side (272 list versus 389). MB says that the same brand should be used as the opposite side. If both were needed I would get the Bendix and save a bundle.
If you were to buy from fastlane I think you will find that the Bendix might not be available AND you will find that brake parts are one area it really pays to shop. The ATE calipers 126 420 06 83 and 126 420 07 83 are going for 191+.
The height valve # 202 320 02 58 lists for 272 and doesn't get much better at fastlane.
Bosch Master, ASE Master, L1
33 years MB technician