i systematically went through some recs from another member here. the usual problem was they didn't ship to me in California USA. what i found was:
They ship in 3 days. Cost was about $33 for 10 ampoules (Rotexmedica B12 depot) and shipping. the shipping seems too good to be true. cross fingers.
(Update 12/10/2020: apohealth.de/ did in fact ship in 3 days! and i got exactly what i ordered. )
Mycare.de was about 3 times that for same product (Rotexmedica B12 depot).
vitaminb12online.com was a super long ship time 30-50 days and about 2 times cost of comparable product.
posting to save other US members the hassle.