check.
N95 masks are for sale on Amazon for less than $10.
Assume a very high quality mask-goggle set costs $20, and that 300 million sets are needed, for a total cost of $6 billion.
Add a generous $4 billion in order to expedite/ship and for overhead and profit, for a total of $10 billion.
To handle any contingencies, double that to $20 billion.
It seems that American industry as a group could accomplish this within 2 or 3 weeks.
I must admit that the resultant savings would be only $3.98 trillion, rather than the full $4 trillion.