Most B12 supplements come from bacterial fermentation except a minority are purely synthetic. There are no TRUE vegan forms of ACTUAL B12(unless you consider synthetics vegan) as the "B12" that comes from plants and algae sources is an analog that actually makes it harder for your body to absorb real B12 and can even contribute to deficiency. Some have said that if you don't wash your hands frequently and don't wash your organic produce you get B12 from the bacteria cells you are ingesting. I myself don't suggest this but "some have said".
Vitacost is the cheapest and the biggest store for vitamins and such.
I get all my supplements from them, they carry Deva brand sub lingual b12
jessie - dont rush to any conclusions as your are new to this new lifestyle, please get a test done first before you start taking vit sup. Sean