The market is priced at the point that the most economic for the business. Apple buying an exploit for $100m is not worth it (to apple) vs the potential loss of life of people who might be killed if sold on the black market. Buying an exploit for 1m prevents them being used to jailbreak, is good PR, and is ass covering PR insurance in case an Apple exploit cause loss of life (‘the seller could have sold to us, but instead they sold it to an evil corporation’).