The average child in disposables uses about 7500 diapers in a two year period.
Using the package prices from the two most popular brands of disposable diapers, the cost ranges from .21 cents to .45 cents each. The smaller size diapers are the least expensive, but a child is in the larger, more expensive diapers for a significantly longer time. For the purposes of this comparison, 0.24 cents per diaper will be used.

The math is fairly straight forward:

Lets add in the cost of wipes!
A budget brand mega pack of wipes costs $9.99 for 400. This works out to 0.024 cents a wipe. Wipes are more expensive if bought in smaller packages or if they are brand name. Some are as much as 4.00 for 80 wipes, which works out to 0.05. Again, if we stick to the lower end of the price range, the math comes out to:

Most likely you will use more than one wipe at during the messier changes.

If your baby uses more diapers, more wipes per bum change, or more expensive diapers, this cost can go up dramatically. You also have to factor in the cost of gas to go and get those diapers.

You could also consider the cost to the environment.

No matter how many diapers you use, two years service will be $1898 before any other discounts!.

With the prepayment discount you save $192 dollars over two years.
With the referral discounts, you could save up to $19.95 for each friend you sign up.
If you have twins or triplets, you save thousands off the cost of disposables!
With the loyalty program, additional weeks cost less.

Here are other potential benefits:

Less Diaper Rash, means less money spent on diaper rash creams.
Earlier toilet training, means less money spent on anything diaper related.
The peace of mind knowing that you are choosing a healthy and Earth-friendly way to diaper your child.