Measure 74 will not force anyone to buy medicine. Nothing about the current program needs to change for a patient. All Measure 74 will do is add dispensaries in Oregon. Patients can still grow their own or designate a grower, but will also be able to go to a dispensary when their crop fails, or is stolen or raided by the cops. New patients can get medicine right away instead of waiting 5 months for their plants to grow.
I don't know where you got the idea that passing this would mean that everyone would have to pay for their MMJ, but that idea is completely wrong. Part 3 of Measure 74 says, " The purpose of the regulated medical marijuana supply system is to supplement the current system which requires patients to produce their own medicine. The system shall not infringe on a registry identification cardholder’s ability to produce the registry identification cardholder’s own medical marijuana or to designate a person responsible for a marijuana grow site to do so for the registry identification cardholder."
So voting yes for Measure 74 means voting yes for the right to use a dispensary if you want to...having more money go to support state programs, enabling scientific research into MMJ, more accountability and regulation, and still having the right to grow your own medicine. Voting yes is the compassionate and reasonable choice.