Here's a decent 52 set. With the proper 6 hole receiver. Might be a good deal if you want an older 500 series set.
http://cgi.ebay.com/Vintage-BELL-Rotary-BLACK-Telephone-Western-Electric_W0QQitemZ200261382852QQihZ010QQcategoryZ38038QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
( dead link 07-14-21 )
That does look like a nice fixer-upper. I just wish that the view of the bottom was better...I can't see if the ringer is present.
Mark, it looks like the ringer is there. You can see the volume adjustment wheel. I can see one gong on the left side but don't see the right side (in the photo). Often the seller will send an additional photo if requested. I have picked up phones where the ringer assembly was there but the gongs had been removed, probably to silence the ringer. Sometimes the ringers were disconnected or removed so that Ma Bell couldn't detect an "unauthorized" phone on the line when ringing voltage was sent to the house.