Everywhere on the Dutch side costs money, yes. And frankly, you don't WANT a place that has no appointments, as then you wait in line, usually in the sun, wasting valuable vacation time. As far as I know, the places that do tests on the Dutch side are listed in the link in the very first post, pinned to the top of the forum. We used Medworks and it was extremely prompt and (fairly) painless. Unless the US drops it's testing requirements, that's where we will go back to in October.