This depends on many things and unfortunately, there is no straightforward answer! The price is down to several factors including which brand it is, and – in the case of marble and granite – where it has come from. The thickness of the worktops is obviously a factor, and some of the cheaper brands achieve a lower price by offering thinner cuts of the marble, granite or quartz.
In the long term, cheap quartz can stain, and the surface can become textured. However cheap granite is rarely a good quality, and this can be spotted a mile off.
We would always recommend shopping around and going to see the material you will be buying, before you commit.