If you don't already have a brand preference, I would probably buy some used diapers (there's a FSOT on Diaperswappers, and I think here on MDC as well?), in a good assortment of brands, see what works for you, and then get more of that type and resell the rest.
People usually say that you need about 12 diapers per 24-hour period for a newborn. So if you take that figure and are willing to wash every other day, you'd need about 24 diapers.
I have a personal bias against AIO diapers (I think they're too hard to get clean, and they take forever to dry)- forgive me if you've considered and rejected this already, but how about pocket diapers? A waterproof outer, a dry-feeling inner, and then you stuff the pocket with something absorbent that dries quickly. FuzziBunz, BumGenius and Happy Heiny are a few popular brands of pockets. There are also a ton of WAHMs who make diapers.
If you're planning on exclusively CDing from birth, you might consider one-size diapers, to really get your money's worth!
Do you know about the DiaperPin? You can find many, many reviews of every cloth diaper and CDing accessory under the sun there to help you decide. Here's a link to the AI2 review section:http://www.diaperpin.com/diapers/ite...asp?subcat=AI2