Field Gear & Protection via Amazon offers Prime members the Soviet Russian Civilian Gas Mask
with free shipping
. (Non-members can spend $25 or more to qualify for free shipping; otherwise, shipping costs $5.58.) That's pennies under our mention from last week and the lowest total price we could find for such an item by $31, outside of the mention below. It's available in sizes S, L, and XL and comes with an NBC filter and cloth bag.
A close price: Trove of Goods via Amazon has it in S or L for $8.99 with free shipping via Prime.