I don't never exaggerate
The only reason those masks need to get swapped out is if they get wet. In surgery, this would be splattering fluids, for example.Realistically, if used properly, I think we’re looking at an absolute minimum of one mask per day. Certainly not a week.
If you’re willing to properly sterilize it, I think you can get an extra day or two out of it.
I may be overstating it cost a bit, but if used properly, it’s still not insignificant for a lot of people…
Most reasonable people at this time are limiting their trips to essentials. Grocery, pharmacy, etc. Out for an hour in very limited exposure and back home. A week is more than adequate for this. A month would probably work as well if you're rotating masks. A cloth cover over an N95 is another option for keeping the surface as clean as possible.
If the DPA was used to make more N95s in America, they would be back down to under $1/mask and then wearing a new mask each day you go out should be very affordable.