Alcantara ist certainly not cheap. It's a premium product.
But, you have to obey a cost perspective, no one wants the absolute best material if it is multiple times more expensive. Always bear in mind that the last few per cent are very difficult and costly to achieve!
I agree with @pauliunas, as it is fitted exactly to the keyboard the chances of ripping it are slim.
On top, as you haven't purchased your Voice yet it makes sense to just hold off and add this to your "dislike" list, there might be a budget plastic keyboard in the future, who knows