I wanted to buy a Sonicare Prestige, (237 SFR) then I noticed that Galaxus sells a set of 4 heads for 37.10 (total: 274.10), but they also offer this set in a bundle with the brush for 284 SFR (almost 10 francs expensive)...am I missing the logic here?

Since this toothbrush comes with a 90-day trial option, many people take it, of course not everyone keeps the toothbrush, but with Philips' 90-day money back guarantee, everyone can test this toothbrush, so everyone is a tester, so to speak.