Does its price really matter for amounts used in chips?
i mean, can you imagine how many chips are built? nowadays there's at least a chip in most physical objects...
And the part that is substrate, not the packaging is tiny and thin. It's much less than a gram of material in CPUs and even less in smaller chips. That's not going to be a significant part of final price. Also remember that silicon currently used is not some regular sand, but grown monocrystals that are a bit pricier.