It's going to depend on the county you move to in California. Not all counties are weed friendly. And I am on medi-cal and they don't pay anything for my mmj needs, they could care less about it. You've got to go to MediCann (or similar medical marijuana rec office), it's 125 buxx to get the recommendation and the card for the first year, 95 buxx for the second year renewal, and the renewal cost keeps going down each year. When you've got your rec, then you're free to buy from dispensaries in your area (mostly SF, LA, Sacramento, Humboldt areas) or grow your own. Now, I used to work at a bail bonds office, and lemme tell ya - just cause you have a card doesn't mean they can't arrest you. They can and they will if you make yourself obvious, regardless of your mj card. This is from direct experience. Not heresay.
If you want to move here for the medical marijuana, look online for California dispensaries, and try to move to an area close to them. Otherwise, in areas where there are no 'storefront' dispensaries, you will have to get your medical mj delivered, and pay much higher prices per oz. I'd say - move to Humboldt!! Everything you want is there.