I was quoted between $350 and $800 with everyone saying
that the Zetec cat is a rare one.
The $350 was Midas, and I'm not sure they read their books
right...
The cat itself from the dealer runs over $600

Make absolutely sure it's the cat. For me a faulty DFPE (sp?)
sensor caused a cat-related CEL error code, much cheaper
to fix.
Cat failure on these cars is rare AFAIK.
T.