Boeing 707
This site lists all aircraft manufacturers. It has all the details on the aicraft you choose. It is very interesting.
http://www.aero-web.org/locator/manufact/manufact.htm
These sites are great for used planes!
http://www.aso.com/
http://www.controller.com/default.asp?kwid=532&seid=2
http://www.findaircraft.com/?source=overture&OVRAW=used%20airplane&OVKEY=used%20airplane&OVMTC=standard