So given the image below (credit not mine):

Ship/Multitool stats post-Echoes

Ships' slots and classes can be maxed out with nanites and units; the only difference between classes of ships these days is the minor advantage one gets to base stats (fighters get a damage bonus; explorers get a hyperdrive bonus; etc.; that's not the subject of my post).

TL;DR: Jump down to "Thus my question" in bold.

I've got a stasis farm producing 16 devices per day that I sell at +4.8%; that plus the gold farms I set up in order to finance the ships/upgrades/bases to create the stasis device farms nets me just under 500m (half a billion) units a day.

However, my 24/32 S-class fighter (a medium-tier, not even large, as you may note above) ran me 45m units for its first additional slot, 50m for its second, 55m for its third, and it says it'll be 60m for its fourth. Earlier slots in smaller exotic ships started at e.g. 18m, then 19m, then 20m, etc. Clearly there's a pattern where per-slot costs jump from +1m each slot to +5m each slot to… where does it end? With my stasis farm, that means I can afford maybe 8 slots per day right now, and in a week, it will be less than one. Base part limit issues crop up once you start farming more than ~32-48 devices per day.

Thus my question: Those of you who are driving ships around with e.g. 60/100 slots (fighter) or 60/110 slots (explorer) etc., what did the final slot cost, and what would you estimate you spent on slots from the time you bought the ship (when it had at most just under 100 fewer slots than its maximum) to when you maxed it out? Based on the progression I've observed, it has to be hundreds of trillions of units unless it finally levels out or I'm missing something here.

EDIT: I guess one alternative would be just starting to farm the ship expansion modules at some point, but I've found a grand total of three in a few hundred hours this save. I haven't been too focused on them, granted, but it seemed like the money route would be faster until I did the math leading to this post.

Thanks for any information!