I'm attempting to keep this short and simple: using cloth diapers doesn't have to be expensive or complicated. Although anyone can do the math and realize that cloth diapering is cheaper than using disposables in the long run, for many people the immediate upfront cost of buying twenty or thirty new cloth diapers is straight up too much. One new cloth diaper can be $18-25, and you can get 100 or more disposables for that price.
Thankfully, it's actually quite easy these days to buy (or borrow) used diapers, making them much more affordable. Most cloth diapers are incredibly durable and can last through many children. Here's a simple run-down of options based on my experience:
BUY USED: We bought used from both a used children's store and from eBay. When searching on eBay, use the word "lot" to search for big groups of diapers being sold at once. Sometimes you'll find diapers being sold individually here and there but if you can find a "lot," you win big, especially if you know what kind of diaper you want to use and can search for it. (For those of you wondering... every used diaper we've ever purchased was sent to us glowing white and free of stains or smells :))
SUPPLEMENT WITH SOME NEW ONES, FOR FUN: I supplemented our mostly-used diaper stash with a few new ones simply because I had to have the panda print diaper and that bright red one, too. Most new diapers I purchased were $10 or under on Zulily.
LEND AND BORROW: I recently had the pleasure of shipping our 20 newborn-sized diapers (which we bought used) to lend to our friends and their new baby. They'll send them back eventually and we might use them again one day or find another home for them. If you've got friends with children nearing the end of their diaper days, reach out and ask if you can borrow or buy their diapers from them!
DONATE: If you don't know anyone locally to donate or lend to, you can wash your diapers one last time with extra care and love and donate them to a cloth diaper bank! Some little baby bum will know the comfort (and cuteness) of cloth diapers that otherwise might not have had the chance to. Here are a couple of choices:
"Since August 2011 we have helped nearly 1,000 families have access to clean reusable diapers. Those families have been able to save over $1,140,000 on the cost of disposable diapers and have kept nearly 3.6 million diapers out of landfills."
By buying used, lending, and donating cloth diapers, we not only integrate our lives better with the planet, we also integrate our lives with our friends and other parents in a sisterhood-of-the-traveling-pants sort of way :)
Finally, if you have questions about any aspect of cloth diapers - buying, cleaning, how to manage cloth diapers on-the-go, etc., please ask and I'll happily respond based on our experience! No one is perfect, and we do not use cloth 100% of the time, (we use disposables at night,) but every little bit helps!