The short answer is yes.  You can buy a used suppressor and have it transferred by completing the proper NFA paperwork.  However, seeing as it will take 4-6 months for the BATFE to approve the transfer most people prefer just to buy a new one.  Some people will offer to pay the $200 stamp tax for the transfer simply so they can unload a suppressor legally.

The used suppressor market is not large in the United States. In contrast, some European counties do not control the sale or possession of suppressors. In these countries, they are widely used and are available second hand just as guns are in the states. 

Suppressors do have a working lifespan and will eventually wear out.  This is another reason people do not like buying a used suppressor.