I did another search for you and found the following suppliers that carry disposable diapers and offer dropshipping services as well - Link hidden: Login to viewLink hidden: Login to view
I suggest getting in touch with the supplier directly to inquire further regarding the prices they offer. Please do not relay right away on the prices you see posted on the sites - an email or call won't hurt.
Just take note that if you might to maximize your profit margins wholesale will be the best route :)
All the best!
Hope this helps.