The 2.0 Zetec is used in cars still manufactured, today. Dealerships, for one, would carry them(there are others). Also try junkyards if you feel more risky..
EDIT: Signature Lincoln Mercury provides CEG members with a 33% discount.
parts counter express
Contact Steve Mullins there...
Also, Tousley ford in Minnesota gives a 50% discount, through the SVT performance plan they have there.. though I am not sure if they will restrict sales to ONLY SVT parts, or not.. you may get 50% off any list price if you just reference the plan.. I simply called and said, "I heard that you have a discounted SVT plan you offer?" and they said sure, what part you need?.. just try that, and say "a whole engine... 2.0 zetec.. etc etc"
Steve
Tousley Ford
1-800-328-9552
Ray