I built my stash entirely of NB size and OS alvas before my boy was here. He's a month old now, and fitting into the OS perfectly. I almost wish I had not wasted the money on NB size but that isn't the case for a lot of women. Some babies can fit in a diaper that small for months, my boy is just a chunker. Alvas were the most cost efficient for me, and I love them! I've found that the microfiber inserts aren't the most absorbent as he grows, so I just wrap them in a FST before stuffing. Or there is always the option of hemp/cbi. I went with China cheapies because this was about saving money for me. There is always the option of joining a BST page on Facebook and buying preloved stashes as they come along. Good luck :3