Get the ones that have 1/2 unit markings.
They have them here, you can buy them from Total Diabetes Supply:
https://www.totaldiabetessupply.com/collections/insulin-syringes/products/bd-ultra-fine-6mm-needle-insulin-syringe-3-10-cc-31-g-x-6-mm-15-64-in-1-2u
But why not get a prescription and get them from your pharmacy, so you would only need to do the co-pay?