You can order 200 tablets for $21.00 from here.For adults, the recommended dosage is 2 tablets per day for 14 days, followed by 1 tablet per day for 71 days. A total of 99 tablets per adult. Therefore, one bottle of 200 tablets would be enough for 2 adults.
Potassium iodate saturates your thyroid system, thus blocking the absorption of the bad stuff.
However, if you're Ben Affleck, you can wonder around for hours and hours in an area thick with clouds of radioactive dust and debris, swirling all about you, breathing it all in while walking and running, with no adverse impact. (See "The Sum of All Fears").