Amazon has U by Kotex Click Tampon Super Plus Absorbency, 18-count Boxes (Pack of 4) for $5.81 each – comes out to $1.45 per box.
Right now, they are an add-on item when you purchase $25 or more. So you can either add them on to another $25 order or you could place five orders (to get over the $25 limit) and have them shipped to your house.
This price is within my stock-up range…and it is even better because it will shipped to your door.
Pricing was current when the post was published, however Amazon prices change often, so please check before you buy.