I came across this chart, and love how it shows how much you can save using cloth diapers:

Disposable Diaper	$0.25/diaper *8760 (8 times/day * 365 * 3 years)	$2190.00
One Size Pocket Diapers	$17.95 each * 24 diapers	$430.80
Sized All in One Diapers	$15.95/each * 3 sizes of 24 diapers each size	$1148.40
Sized Pocket Diapers	$17.95/each * 3 sizes of 24 diapers each size	$1292.40
Fitted Diapers	$14.95/each * 3 sizes of 24 diapers each size plus 6 diaper covers per 3 sizes $12.95/each	$1309.50
Prefolds System	3 sizes of 2 dozen prefolds approx $22/dz plus 6 diaper covers per 3 sizes at $12.95/each	$497.10