I always recommend that you get as many dipes/training pants etc as you would need for regular diapering. Try to figure how many days you are OK before needing to do laundry and make sure you have enough to last that many days of all misses. The main deterrent to EC is stress, so if you're gonna be stressed over using up all your dipes in one day, make sure you have enough for 2
Lots of people use prefolds just under baby's bum, so those would be really handy and their pretty inexpensive. The other thing to keep in mind is that newborn pee a LOT, and you'll be so concious of wet dipes that you'll probably change more often than if you were full-time diapering.
Personally, I am planning to have some aio's for going out of the house, a few night dipes/covers (as I am not planning to attempt night-EC and want to be covered) a bunch of tiny training pants and fitteds to use without covers around the house and some preemie and infant CPFs for lying nakey baby on. I'm sewing most everything myself, so I use very little soaker padding, and for any dipes that I buy, I request only 1 or 2 layers in the soakers since I don't need a lot of absorption.
The best thing is that you might need a lot to start out for the first few months, but as they get older and you get more in-sync, they need fewer and fewer. By the time my son was 1, we just had about 6 trainers to use at home and a few going-out/night pants (we used 'sposies for most of those until about 18 mo) I don't think I ever had more than 8 pairs of pants at a time after that first year and lots of times those would last at least half a week or longer
bottom line, get whatever will keep you from getting stressed and only worry about the first 6 mo to a year for now.

Personally, I am planning to have some aio's for going out of the house, a few night dipes/covers (as I am not planning to attempt night-EC and want to be covered) a bunch of tiny training pants and fitteds to use without covers around the house and some preemie and infant CPFs for lying nakey baby on. I'm sewing most everything myself, so I use very little soaker padding, and for any dipes that I buy, I request only 1 or 2 layers in the soakers since I don't need a lot of absorption.
The best thing is that you might need a lot to start out for the first few months, but as they get older and you get more in-sync, they need fewer and fewer. By the time my son was 1, we just had about 6 trainers to use at home and a few going-out/night pants (we used 'sposies for most of those until about 18 mo) I don't think I ever had more than 8 pairs of pants at a time after that first year and lots of times those would last at least half a week or longer

bottom line, get whatever will keep you from getting stressed and only worry about the first 6 mo to a year for now.