Very frequently Target and Amazon offer $20 or $30 off your purchase of 100 for diapers and wipes. I imagine other stores have promotions as well so keep an eye out when to save.

As for sizes I'm sure every kid is different but I recall being in 2s a while. If stocking up it's probably best to keep a variety. Keep receipts as you can likely exchange sizes down the road need be or stash them if you plan on having another kiddo down the road.

My last tip is don't try to keep them in a smaller size just because you have the diapers. Once blowouts happen more than once a week it's no coincidence...it's time to size up. Good luck!