Buy coasters? With your hard earned money? I think not!
Just order a load of free tile samples - there are so many tile retailers out there that you’ll be set for life. If you want to be really fancy you could stick some felt on the bottom to ensure a scratch-less experience.
Have posted this before but there’s a chopping board in ikea the exact width of the inside of a fridge which i realised when chilling some sausage rolls before cooking
So i use it as an extra shelf all the time now which is really handy
It’s been serving me as a shelf for 3 years now, if anything its better than the official shelves (it slots onto the shelf holder uppers, its not just jammed in).