I believe that you are talking about the drive belt (aka serpentine belt) and NOT the timing belt.

Try one of the following parts places:

http://www.fordpartsonline.com/
http://www.shamrockparts.com/

You will probably have to call them or write them an email to get a quote.

I believe that the part # that you are looking for is 6B209 (2.0L drive belt tensioner).

1996 Contour SE Sedan 4D (Royal Blue)
Duratec V6 2.5L 24-valve DOHC
Automatic
75,000 miles
No Mods (unless you call the DMD a mod)
Replaced EGR valve (gunked up), EVR (EGR VR), PCV valve, and evaporative emissions hose (cracked).