I used pocket diapers a lot with ds1. Some of my FBs were shot after just one bum! (Even though I liked the fit, I won't buy them again.) So I needed to get more diapers in rotation cheaply. I bought some flats and pulled out some Thirsties I hadn't used in a while. I pinned for a bit which helps contain poop. For now I'm padfolding. The pockets I have that are still functionable I use them as covers with a padfolded flat. With padfolding and a mostly BF baby (we do BLW style solids - no purees), the poop is pretty much guaranteed to get on the cover/pocket that is being used at the time. I have enough that I just toss it all in the wash.
I am also very glad to be rid of the microfiber inserts because of stink issues with them.
I would say yes it is worth it to get CDs even if you only intend to use them on one baby. Some of my diapers only made it through one baby but I firmly believe they still saved us money.
To save money, Diaper Swapper ladies love Cotton Babies seconds, well loveds, last chance diapers. I've bought a Flip cover and a BG 4.0 as seconds and I think both just have a bit of crooked stitching. Entirely cosmetic, barely noticeable, 100% functional. I actually really like the Flip cover and would buy more if I needed more covers. Recently they sold some last chance diapers: 12 diaper for $24 but some of those diapers require repairs. I missed that sale which is good because I might have caved and bought some!