i do prefolds with thirsties brand covers. you can buy all of this used in fsot on diaperswappers.com
as for how many...i will copy some txt that i sent to a friend recently:
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i had 54 orange edged newborn prefolds (GMD). i forgot that they pee 10-12x in a day at first.  i could have gotten by with 30 but it was nice to have an extra day to stretch laundry day.
i tried kissaluvs but didn't care for them. they are cute and fit nice but i seriously love prefolds. hands down.
i was lent some second hand bumgenius and hated them. they leaked like crazy and stuffing and unstuffing them drove me crazy. Â they could have leaked b/c dd has no fat on her thighs...i know people that love them but have heard that over time they get stinky and you have to strip them to make them absorbant again (i have heard this of prefolds but have not needed to ever strip them) oh and the velcro wears out pretty quick.
i also tried happy heiny all in ones and at the smallest setting they didn't fit dd until 3 months or something but i had the same issues as the bg's.
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then i pretty much stuck with thirsties.
for newborn i had 8 covers. on a typical laundry day with a newborn i had 4 covers in the wash. so maybe i could've gottne by with 5 or 6?
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the orange edge lasted 3 months but some people don't get those and just start with yellow edge (dd was a small baby and slow to gain weight. she's still 3% for weight...but if your baby is a chunky one they probably will grow out of orange edge fast. Â they were just nice to have when she was itty bitty (and resell well so i'm not worried about it)
so at 3 months we switched to yellow edge gmd prefolds and i own 30 prefolds (and 3 thirsties small) and we do laundry every 3 days and have about 2 covers per load. plus we were dong EC pretty regularly at htat point so you may still be doing laundry every other day.  you could always get by with less diapers and do laundry more often.
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at 5 months, dd was 14 lbs and was awesome at the potty so laundry was every 4 days and the yellow edge gmd's are getting snug.
at 5.5 months i switched to red edge gmd's and she's in thirsties small. at this point i own 18 red edge prefolds, 3 thirsties medium covers (and 3 thirsties smalls as backup) barely 1 cover in a load of laundry b/c most poops are in the potty.
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somewhere around 7 or 8 months diaper laundry was once a week but that was b/c she used the potty so much.
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and apparently i stopped keeping track at this point but we're in brown edge gmd's right now and we switched to those at 13 months? we have now 18 brown edge prefolds and 1 thirsties duo size 2 cover. i do laundry once or twice a week.
she sleeps in homemade lanolized wool pants but under that is a prefold layered with a babykicks hemp soaker (
http://www.babykicks.com/productInfo/JoeyBunz.cfm)Â and a fleece blanket cut up to the size of the soaker so that way if she pees at night the hemp soaks up most of the pee and the fleece keeps her dry. but she doesn't pee at night anymore. maybe once a month? Â i love the hemp soakers and got mine all used off diaper swappers.Â
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hope this helps!