You need a red card (or the proof that you applied for one) to buy at a dispensary, 2 oz max. You can probably go to several in a day, but you are not supposed to, also driving around with an amount above 2 oz per patient or 1 oz per 21 and over adult without a card, is illegal. Be sure it is not in reach of the driver too, has to be stowed/secured when in a vehicle. Feeling lucky?