Vials of Cyanocobalamin (B 12) have been difficult to get. Often doctors write an Rx for you to have filled at your local pharmacy.
The vials also come in different sizes from single dose 1 ML, 1O ML and 30 ML.
Some people have found it's less expensive to get the a larger bottle and simply pay cash then to purchase just the one month supply with their insurance. That is a case by case situation.
Some patients inject the B12 into the thigh themselves.
This of course is not medical advice.