Cool critters... I had never heard of those before. Maybe they're not sold in Austria; I only know about triops longicaudatus kits, which are very popular over here. Not that I had one of those, either.
As a kid I was more of a put-on-wellies-and-look-what's-in-the-stream person. Trichoptera larvae are awesome (we had the kind that builds and drags around cylindrical silt-cases).