My son may be four years old but we still stock up on baby wipes pretty steadily. Right now Amazon.ca has Pampers Wipes 16x Refill Boxes on sale and there is a $4 Amazon Coupon, so you will be paying $15.97 per box. That is quite a discount from what other retailers have them for.
Baby Wipes are not only convenient for diaper changes—we use them for a ton of things in our household. We use these wipes for impromptu hand and face washings before going into a store, and even for wiping our dog's face (she gets stains around her eyes).
At Amazon.ca, you'll need to spend $35 or more to get free shipping unless you have an Amazon Prime membership, in which case shipping is free on these items.