As far as actual cash, I've probably MADE money so far by using CDs
. I traded for pretty much all of our original stash, a great variety of used dipes. At first we used mostly fitteds with proraps and wool wraps (biobottoms, nikky). My favs were NB Mutts and some random mama-made fitteds. When they grew into smalls, we used other fitteds, prefolds, a variety of covers (I liked the BSWW best at this size, although I would have liked wool but didn't have any) and some fuzzi-bunz. When they grew out of smalls, I sold off all the NB & small dipes on the TP. Several people got good deals, and I made back all I spent and then some. Then I bought 6 FB seconds and some microfiber towels. I traded again for more FB + hemp inserts and a few more times
for some various fitteds. Our current stash is about a dozen FB + 3 FB with shot elastic that we use at night, 1 HH, 2 Happy Hempys for nighttime, maybe a dozen random fitteds, and probably 8 covers. It's way more than we really need and I keep meaning to try to sell some off. But it's also nice to have the flexibility to waiver between using pockets and fitteds, depending on my mood. My gripe with fitteds is the drying time. Oh, I also like prefolds, and have about a dozen of those in the sewing room that I'm in the process of trimming. Those I got off Freecycle.
So, to cut costs & if you don't mind used dipes, try the TP here, Ebay, and Freecycle. How many you need depends a little on what type of dipe you use, but 18 would suffice, I'd think. You can always just wash them when you get low....and/or
keep some sposies on hand until you have a system down that works.
As for what might work, you sort of need to be able to adjust as needed, which is why I didn't want to put any actual cash up front. I discovered that one of my guys gets a very raw bottom in anything other than hemp (we tried cotton prefolds & fitteds, fleece pockets/liners, and sposies). So for him we often use the FB as just a cover, with the hemp "insert" trifolded inside or a hemparoo layed inside a fitted. While ds1 gets a MF towel inserted into the FB or a fitted.
All this to say, it's definitely been worth the cost savings for us. We wash nightly, which is no big deal. And our washer is in the basement, which makes no difference really. Good luck
ETA: I think I may have some small covers (diaperaps) and maybe some NB size (up to 15 lbs) prefolds left. If you're interested I can check. You could have whatever I find that you could use for the cost of shipping.