Replacement brush heads for electric toothbrushes (we use Philips Sonicare, but it’s most likely the same with Braun Oral-B) are ridiculously expensive. The cost CHF 10.– or more PER HEAD. Even when ordering them from Amazon Germany it’s not much cheaper.
What is available on Amazon however are third-party brush heads compatible with Sonicare, although quality remains a mystery. Anyone know a brand with comparable quality to the originals?
These work wlth Sonicare. The price comes to <2 Euro per head, but it’s only available in Germany dm stores AFAIK.
You can get them for more money at Galaxus (still cheaper than the original), but if you are ever in Germany, just buy them there in any dm store.
I was/am satisfied with the quality (also use Sonicare).
Thank you for the hint. We also use Sonicare since some years and so far always paid for the expensive original heads… I’ll try to be brave and give alternative products a try by my next replacement ! 
Simply go for bigger packs (x8), they’re way less expensive than the 4 or even worse 2 packs.
Ex : https://www.galaxus.ch/fr/s6/product/philips-sonicare-hx606813-tete-de-brosse-a-dents-electrique-8-x-tete-de-brosse-a-dents-16221108 (32.-)
Amazon price : 26e
Never tried compatible ones but there are 8 packs for about 20.- on Galaxus too.
I get some random ones with funny names (mitbuty, demirdental) from Amazon and they’ve been alright.
I’ve got mine from Aldi, but it seems they are not available anymore: EASYHOME Ersatzzahnbürsten, Sonic, Dunkelgrau | ALDI SUISSE
I use a Soocas toothbrush. Got it from Aliexpress but nowadays you can get them from digitec. I am perfectly happpy with it
Temu
8 (original) pieces for 33chf, not too bad:
https://www.digitec.ch/en/s1/product/philips-sonicare-w2-optimal-white-8-x-toothbrush-heads-16221108
… or, dare I say it, consider acquisition from beyond the shores of the Hochpreisinsel - €26 as I write this.
Now also in Lidl (3.99 CHF for 6), although 2 of 3 Lidl i checked they were already sold out after 2 days (started on 14.10.). 
I don’t get why Lidl and Aldi are the only ones who actually sell them (sometimes) as cheap as they are sold in DE… e.g. Galaxus is not even close.
The cheapest in Coop and Migros are more than 20x the price (~15/head). 
https://www.lidl.ch/p/de-CH/ersatzbuerstenkoepfe-6er/p10026683
