The most affordable long-term overnight option is always going to be cloth. There's a big initial investment in diapers and plastic pants, but if taken care of, they will easily hit break-even with disposables within the first year, and last several years per set on the average.
There's a huge variety of disposables available right now, in a wide range of capacities. Logically, better capacity costs more. So you're going to have to figure out what you need, and then find the lowest price point for that capacity. There's no one right answer for questions of "best value" where needs vary.
If you're talking about TotalDry XPlus, those are the medical base model for the bambino classico/bianco/teddy. Quality is high (they're good at not leaking), and capacity is enough for the average person for overnight. Don't mistake them for TotalDry Plus, that's the same shape but
much lower capacity. Buy a bag to sample.
They are probably a bit higher at bambino's page, but I see two bags are $60 shipped (
https://bambinodiapers.com/totaldry-xplus-briefs-c-9) A case of 48 is $84 shipped. So about $2/pc, which is a bit high. It looks like they've raised the price on them quite a bit, they're now almost identical price to their ABDL variety.
I did a brief google search and can't find them a lot cheaper, and most of the hits there aren't adding in shipping, so probably ends up around the same price. *shrug* Good diapers ain't cheap.
ABDLShop sells Carousel diapers, which are the same physical model but better padding than bambino's regular diapers, and they cost less. (go figure?) $140 ships a case of 80. If you're okay with the pattern but want to try something similar to that model, I'd suggest carousel. Their storefront doesn't seem to be working right now though?