If you do decide to go the disposable route, then may I suggest a few couponing websites, such as couponmom.com, survivingthestores.com, and commonsensewithmoney.com. These sites focus on using coupons and sales to max out your savings on pretty much everything at the grocery store, but most of the ladies that run these sites are moms, and will focus on the baby stuff. These sites helped us out a lot in learning how to get the best deals on diapers, wipes, all sorts of things.
Some of the tips we learned that we found most useful was buying multiple sunday papers (to get multiple copies of the coupon brochures in them) or asking family/friends if you can have their coupon sections. They also show matchups with sales at varioous stores, especially drug stores like CVS and Walgreens. Both of those stores have in store cash back systems (think Best Buy Reward Zone, only you get the credit faster) CVS has a card that you have to sign up for, walgreens is just a print out from the register. Anyway, we learned from those websites I mentioned how to use coupons matched with sales at the drugstores along with the reward programs to get big packs of diapers are low as $3.50/pack and we even scored wipes for free using coupons. The trick is to buy the stuff when the store is offering a reward incentive, then roll that incentive (along with a coupon) back into more product. (the website can explain it better than I can)
Anyway...yeah, I know it sounds like turning into one of those 'crazy coupon ladies' but it helped us out a lot.
Good luck, and congrats on your new arrival!