On the other hand, if you invest in reusable/washable breast pads, you may spend an average of $8 for 6 pads. This, of course, means you would have to buy at least two boxes for an almost-week's supply at $16. Or, if you don't want to do laundry quite as often, buy 3 boxes at $24. Initially, this is significantly more expensive than $6.64, but since you won't have to buy any more pads again ever, that's actually $80 per year (disposable) vs. $24 per year (washable)--a savings of $56 the first year. And if you breastfeed more than one child, washable breast pads will save you an additional $80 each year that you use them.
I am lucky to have been given all my reusable breast pads, so I've never had to buy any--and if you're handy with a sewing machine, you can make your own. If you're like me and you have three children, whom you breastfeed for a year each, using the above formula, washable breast pads would save you at least $216. And prevent 2,136 disposable breast pads from going to a landfill!
(Of course, be sure to research the product before buying, as there are a few different options out there and not everyone likes the same thing. Also, many experts will tell you not to wear pads with plastic backing, as they can cause yeast infections. Here is one article with ideas on what to look for.)