Agree, but be careful where you "load up". Costco has been pretty good since their prices don't change. If you end up having a big box of 1-2s and need to move to 3s, it can be a problem.
Formula is a totally different animal. I would NEVER buy formula online. We've had issues with food items from
Amazon due to the storage and shipping environment. I nursed and supplemented with Similac, which is rarely onsale. Target has a buy 3 get $5 GC deal every now and then, that's about it. Otherwise it's cheaper at Costco/Sam's.
If you can, try pumping. Most offices are required to have a nursing room. Paying $200 for a pump is a lot cheaper than formula, it's a plus for your health and the baby's.
And our current choice of wipes is Huggies One and Done. They are awesome! We keep a pack on the kitchen table.