I haven't looked at any prices lately, but are you sure you're looking at them correctly? Does a moth's supply of monthly disposables cost twice as much a month's supply of daily?

Monthly contacts usually come six in a box--enough to last for 90 days, while dailies typically come 30 to a box, which will last 15 days if you wear a pair every day. Only one sixth as long.

So if you're comparing the cost of one box of monthlies to what one box of dailies cost, your calculations are going to be a bit off.