Clean and ready to use = $500-600/
pr and should move them quick. More if they were a matched set and/or freshly restored to the same finish.
As-is (need rebuild kit) and perhaps still dirty = $400 and might move a slower.
Used parts are often valued heavily based on condition. Some don't care because they will restore and 'get their hands dirty' anyway. Others value ready to bolt on with a big premium.