Inexpensive sublingual B12

I can't do the sublinguals. I was doing injections long before my WLS and have to do them 3 times per week.  It is amazing how much I need of the stuff.  When I was in the hospital last winter I didnt get my shots for 2 months, did get 1 IV bag of B vitamins though and when I saw my surgeon for follow up, my B12 level plummeted from 1800 to 400, she freaked out.  Had me go onto daily shots for 2 weeks and then back onto my normal routine.  then just this past month I forgot a few shots and only did them once or twice a week and just got my B12 level back my hematologist did and it was 700.  I just can't believe it.  I really have to do it 3 times per week.  I used to do it that often due to chronic fatigue syndrome to get extra energy and somewhere along the way I became B12 deficient but we dont really know when since I was alway on the injections.