Okay, I'm probably late here. But anyway, let's shake it up. I'll use M4 as it's well-known for fair price and performance.
Abena M4:
Look up from Amazon the prices have changed from (lowest) $47.98 ($48) to $57.23 ($57) (all in USD) in the last 120 days (I checked the one from seller "Engloids"). In average/mid price we find $52.60. The prices are for 3 cases of 42 Abena M4's.
Use:
I have been using Abena mostly and I could say it have a pretty decent performance, although I've never tried abdl diapers, and not really interested to try because it's very pricey and I think M4 already done a very good job (or I'm just in love with it).
Sometimes I change 2 times, 3 times and 4 times. Very rarely (close to never) done more than 5 changes.
2 change/day: 10%
3 change/day: 70%
4 change/day: 20%
So I put the amount of time of changes/day in percentage (It's not very accurate, but I'm pretty positive about the numbers).
So if 3 change a day, then * 365 = 1,095 diapers/year
1,095 / 42 (is the diaper of each time you buy 3 cases of 42 from Amazon) = 26 (.07, there is some decimals but I'll round it up)
26 orders and each is * $52.60 = $1,367.60/year just for diapers.
Additional:
I've been going off 24/7 lately and stuff that I need are only powder, rash paste, and wipes.
Johnsons Powder 15oz: $4, used it all the time and it's more than enough for a month.
Desitin Rash Paste 4oz: $5, I use it every other day even without having any rash (just to be safe). Enough for a month and sometimes more than a month.
Huggies Wipes: $6 each, comes in 64 wipes. I usually need 3 of these each month. So total is $6.
All total is $15 each month * 12 = $180/year
Overall:
1,367.60 + 180 = $1,547.60 per year needed for 24/7 in diapers. I mean prices could change, but this is the very closest estimation I guess.