I am approached by friends and colleagues selling their used bassoons from time to time.  I will post those instruments here.  I also can help put you in touch with sellers of new bassoons.  Please seek assistance when buying a bassoon from an experienced bassoonist and go with a reputable seller.  I encourage students pursing music degrees to purchase Fox 240s but not exclusively.  Bassoon prices are usually open to some negotiation.  I will add some articles and information on purchasing as this page grows.

How old is the Fox (or Fox Renard) Bassoon?  Handy table listed here:
http://www.foxbassoons.com/fb_serial.html

No private sale of used instruments know of right now.