Insulin syringe sourcing — best prices for 31G 1/2cc syringes

Adding the numbers, since they settle part of this. Red flags, in rough order of how much they should worry you: no verifiable address, no batch numbers, prices far under market, vendor-commissioned tests only, pressure toward irreversible payment, and shipping with no temperature control.

A narrower follow-up, since the general answer is now clear:

How much material I am losing to dead space, and whether that explains why a 10mg vial gives me nine usable draws rather than ten?

hank_denver said:

Red flags, in rough order of how much they should worry you: no verifiable address, no batch numbers, prices far under market, vendor-commissioned…

Coming at hank_denver’s question from a different direction. Prices dramatically below market are the strongest single signal, and the reason is arithmetic rather than suspicion. Synthesis, testing, and cold-chain shipping have floors. A price well under the floor means something was skipped, and the two things that get skipped are testing and content.

Worth separating that from vendor vetting, which this thread keeps folding into the same question. They behave differently and the advice does not transfer.

OP back with an update, since a thread like this is useless without one.

Resolved. I wrote mg, ml and mg/ml on the vial in marker and did the division in that order, and the two of us now get the same number every time.

Dr.EM_Chicago said:

Prices dramatically below market are the strongest single signal, and the reason is arithmetic rather than suspicion.

Agreed, and it is worth saying that rounding to the nearest whole unit is usually acceptable at maintenance doses and is not acceptable at the bottom of a ladder, where one unit can be a fifth of the intended dose.