You won't be able to fly into Schiphol, or any other controlled airfield for that matter, without mode-S, as mode-S is mandatory in a CTR (class C airspace).
But uncontrolled fields like Lelystad and Hilversum can be reached easily by way of class G airspace only, and by staying below 1200'. In fact, when flying in the west of the Netherlands, you are limited to altitudes below 1500' anyway due to the Schiphol TMA which is class A and starts at 1500'. And remember that this bit of the Netherlands is below sea level so there's not a lot of high ground to worry about. Just the occasional tall TV tower like the ones near Hilversum and Lopik.
Even with mode-S, Schiphol would be very expensive. Expect not much change from 300 euros after you've paid for landing, ATC and handling. Hilversum or Lelystad are much better options in this respect. And even Rotterdam will be much cheaper.