If you had exactly 100 pills that could cure cancer, how would you decide who to give them to?
First, I'd make every potential buyer fill out a "common application," including, as a part of this common application, scores from an 8-hour examination detailing their understanding of the disease.
Due to mystery magicks, this common application will take "some time" to be processed. After processing of this application, and receipt of upwards of $500, I'd send everyone a "secondary" application, depending on their type of cancer. For some cancers, they'd just be asked to send in an extra $75 dollars and write their name again. People with harder to cure cancers, will be asked questions such as "Why do you want to be cured of cancer?" and "How will curing you of cancer lead to increased diversity of the human genome?" Those with the hardest cancers of all to cure will be asked questions so lengthy and ambiguous that they are forced to give up immediately. All secondaries will require extra money.
After receipt of the secondaries and payment, absolutely nothing will be done. Unless payment wasn't received, in which case we will make sure to quickly notify the applicants. Nothing will be done for months. This will give time for some people to die, thus lowering the applicant pool. After a few months, we will invite people we have an interest in to come interview at our hospitals. To those we are not interested in, we will most likely say nothing for a few more months. While we will not charge money for the interviews, we will also not offer financial assistance to those coming from a long distance. At the interview, any trace of humanity will be noticed and considered a negative factor in the review of their application. People will make mental notes of everything they say, and especially how they are dressed. The interview will last anywhere from 20 minutes to an hour and a half. At the end of the interview, we will say nothing about the status of their application. We will wait a few more weeks, giving time for more people to die.
At this time, we will begin to hand out our 100 pills. Only to a very select few, of course, those who have the ability to play this application game the best. Those who we are less interested in giving the pills will be put on a waitlist. This waitlist will last until the apocalypse or we run out of pills, whichever happens first.