Check with PartsShop. This is one of those items where the same part is available significantly cheaper in the aftermarket.
I gave a list price so that you could compare. I could supply a new pump for nearly half of that list price, I'm sure PartsShop could do similar.
I say this to save you from spending 50% of list on a used pump. Most salvage yards are going to be reluctant to sell that pump off a complete motor, as it will leave the insides open when removed. They also will sell the motor with a pump so they won't want to break it up.
Any used pump will probably come from a "core" motor (one that has failed and is being parted out). This is likely to have more miles and/or some of the failure left in it.
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician