Ebay's Required Disclosure for Medical Equipment:

"The sale of this item may be subject to regulation by the U.S. Food and Drug Administration and state and local regulatory agencies. If so, do not bid on this item unless you are an authorized purchaser. If the item is subject to FDA regulation, I will verify your status as an authorized purchaser of this item before shipping of the item."

If you have questions about legal obligations regarding sales of medical devices, you should consult with the FDA's Center for Devices and Radiological Health:

Links: http://www.fda.gov/cdrh/devadvice/ or http://www.fda.gov/cdrh/industry/support/index.html