Question about Netatmo Smarter smoke detector set of 3

Although the prices at Digitec/Galaxus are relatively cheap, I have also noticed that some prices are illogical or show unbelievably high fluctuations within the day. They call it "up to date", I call it, you don't really have it under control. But nowadays you have enough possibilities to compare, so they risk that you buy somewhere else or, as in this case, I would cheekily order the individual item, or at best even individually and separately.