Hi,
I buy my ProZinc from the vet at $103 per vial. I've read that Costco carried it, but my local one (S. California) does not. If you're careful with the vial (not shaking it, refrigerating properly, not dropping it, etc.), it lasts months rather than just the 28 days after opening it, as stated by my vet's staff. Do check the expiration date before purchasing it and ask for one with about a year's duration.