is the piggybank size or amount the player has meant to have an impact on the purchase price/sell price of an item?changing the bank size has been causing everything's prices to change.

No, it has no impact on pricing. Prices fluctuate naturally for about 3-4% on average (max ~11%). Keep some bookmarks open for some time and remember their prices. You will see some changes over time

that makes sense. but i mean like some items have gone from costing from 1000-40,000 all the way up to 1.783e+10

Hmm .. that might emerge from some incompatibility with some mods. Which mods do you use?

all the mods. lol. 173 mods in my current testing client. mostly omnimatter, angels, bobs, yuoki just to name a few. i'm going to try a hard reset of the mod to see if it resets things (remove the mod, load and overwrite the save file. then re-add the mod).

I've noticed some incompatibility with yuoki. I will fix it when there's some free time to do so.