Woah! $100? I guess it does come with 1 $20 filter as well.
How much are OEM fuel filters, like $60?
The OEM filters are not that much, but:
1) they do not do nearly as good a job of removing particles from fuel, and
2) they are supposed to be replaced about every 20k miles.
If you pay $20-30 each 20k miles, then the cost of OEM filters adds up. On the other hand, the Cat 2-micron filters are good for up to 100k miles and the replacements are only about $15.
So a Nicktane kit will pay for itself in roughly 60k or 80k miles. And after that the savings just continue to add up.
And there are no moving parts, so you can move the filter kit to your next TDI, and the one after that, and so on. Or to a gas-engine car, too, if you ever decide to go that way -- super-filtered gasoline is just as good as super-filtered diesel.