You forget to add in the R&D used to create said drug, the FDA Fees and costs to get the drug tested and approved. Now add in the Liability costs when shit happens to %.001 of the people taking the drug and are sued into oblivion by the likes of John Edwards and so on.
The real cost of a vaccine is probably closer to $200 per dose than the actual $1 cost to manufacture it.
Now, if you're suggesting we stop R&D, FDA approval process and torts against the vaccine manufacturer then we might be closer to getting your fictional $1/dose vaccine.
It just isn't as simple as you suggest.