Help! We booked our flights into Brussels, rather than Amsterdam because there was a $250 savings. We thought thalys had 25 euro saver tickets, but can't seem to get them online. We are looking for two adult tickets, May 29th, a Saturday. Are these tickets not available on the weekends? We'd be totally open to slower trains for cheaper tickets! Help! Is booking ahead online the only way to get inexpensive tickets?
The normal ICE link between the two cities is only slightly slower than Thalys, and it never sells out. Last I checked, it was 35 euro one way. You can catch it at any of the three Brussels rail stations (whereas Thalys only stops at Brussel Zuid). For an even slower option and slightly cheaper option, you can take an NMBS (Belgian rail) train to Roosendaal in the Netherlands and hop on a NS (Dutch rail) train from there.
The regular inter-city trains between Brussels and Amsterdam are an hour slower than the Thalys high-speed. The Fyra service currently only runs between Amsterdam and Rotterdam.
The €25 Smoove fare discount tickets are available any day of the week, but they are sold out for 29 May. (The allotted number of tickets go really fast, especially on weekends.)
If you book any kind of discount fare for Thalys trains, you have to be sure to leave a generous connection time between your flight's scheduled arrival time and your train's scheduled departure time. If you miss your train, you will be out the price of the ticket.
The current total fare for a regional train from the aiport to Brussels plus an IC train from Brussels to Amsterdam is €38.40. Buy your tickets at the airport and jump on the next train.