We've been using the Wolfsblut range (a DE brand) that we get from Petcenter.ch for about 4yrs now. Not the cheapest but keeps our Bobbery pack happy.
We also use Zooplus - and if you spend a certain modest amount (=1 to 2 bags), it really is free delivery, no surprise costs. And it gets delivered and left on your doorstep so you don't have to lug it home from the shops. It's a win-win (except for Coop and Migros).