For a '95 Contour V6, the harness kit was $600 (it includes 4 harnesses)

The Zetec one should be cheaper, because it only includes 2 or 3 harnesses, and they are not as complex.

'96 and newer cars should be cheaper, because they use the newer style connectors found on current Ford vehicles, unlike the '95 which uses older style connectors that are likely more expensive due to being made in smaller quantities.

I base that on the fact that the injector harness, by itself, for a '95 V6 is about $400 while the injector harness for the '96 V6 is only about $200.

Yes, this means that the harness kit is a MUCH better deal than buying all the harnesses separately.