https://syringesneedlesdepot.com/
They sell single vials or packs. They currently have a coupon code NEWCUST for 10% off on first time customers. Bought a 5 pack that cost me about $13.80 each after shipping cost. Free shipping over $199.
Underground Supply has them cheaper with free shipping over $99 but they're away right now and not taking orders until 04/11. They also sell the Hospira in kits if you need other supplies. I never ordered from them but have seen others on Telegram groups and forums mention them.
https://www.undergroundsupply.shop/product/hospira-bac-water-30ml/