As I understand it they lease the machines but even then the cost of the lease is taken out of transaction fees from purchases. Essentially it costs the dispensary nothing.
If the dispensary has to pay someone $15 an hour to work behind the counter, and that employee makes 15 sales an hour (for arguments sake), then the dispensary cost is $1 per transaction. Zazzz will take the same $1 per transaction, except it won't get sick or steal while keeping track of inventory and advertising. People that have questions can go to the counter, everyone else can just go to zazzz.
In summary: There are no financial barriers for entry into the dispensaries and zazzz will only make business easier and run smoother. It's friggin brilliant.