35,000€ for a ceramic slab is acceptable, it just depends on the size. Our stonemason had natural stone slabs with a square meter price of up to 35,000€.
Who can afford it and wants to... why not? After all, stonemasons have to make a living too. Meanwhile, I'm wondering whether a continuous slab is really worth 600 euros to me or if I'll just pay 180 euros for three individual slabs.