I'm surprised that there is nothing like this in Canada yet, at the right price I might be in on something like this as a new way to experiment with juices. For 25 or 30/month for 5 or 6 10mls plus a small discount for reordering one of the monthly flavours during that month for subscribers would be a great way for a small vendor to bolster sales.
It gives the vendor a guaranteed monthly income, plus gives them more brand recognition. Unfortunately there aren't many vendors with enough of a flavour base to keep it continual. You would start getting repeat flavours very quickly. Juggle could pull it off, MLV and Canvape maybe.
Set your pg/vg/nic level upon signing up and wait for vape mail.
Even a Netflix for vapours would be cool, where once a month you could order 5 or 6 10 ml bottles for a monthly fee and then again get a small discount if you reorder the same flavour during that month. If you order nothing you still get charged unless you cancel within a certain timeframe.
The only problem with it is most vendors don't use via/mc therefore cannot use reoccurring charges. It would be difficult to set up logistically.