If you follow Craigslist you'll see them come up fairly regularly and mostly get sold fast.
Here's a link to a web site that allows you to pull up listings from all of craigslist at once, just plug in "four wheel camper hawk": http://www.searchcraigslist.org/
Unfortunately, if the listing has been taken down you can only see a couple of lines of text that don't generally include a complete description of the camper or sometimes even the price.
There are some other search strategies listed on page 152 of the Used Pop Up Camper Alert thread: http://www.wanderthewest.com/forum/topic/7380-used-pop-up-truck-camper-alert-thread/page-152
To see complete ads for campers which have sold you can find some on the gear exchange thread on this site: http://www.wanderthewest.com/forum/forum/15-gear-exchange/
or Expedition Portal's camper and trailer for-sale section: http://www.expeditionportal.com/forum/forums/99-Expedition-Campers-and-Trailers
Or you might just try calling or emailing someone at FWC. Stan is particularly helpful, and has helped FWC owners sell their campers on this web site.