I feel for you OP. I could write a book about this but here's my 2 cents. Assuming you're an American.
If you're in USA then I'd recommend you check out some of the stuff at JCrew. I think they finally realized people in their target don't want to buy trash, so they upped the quality (meme) on a lot of their stuff. Mainly the shirts with the label in pic related. The ones with the other label are starched, gaudy, and designed for low iq bros.
This guy is in the same mindset imo. If you're not trying to "make waves" but look fashionable in an otherwise normie setting these are a good option. Will say I'm noticing some strategies with company that suggest they are in a phase of sacrificing some quality for profit, though. To what extent I'm not 100% sure.
Yes, you will need to spend a premium for good business casual shirts. Both of the stores above frequently have good sales though, so you can buy some basics en masse and have yourself covered. The cheaper shirts from low end retailers WILL deteriorate quickly and probably isn't cut for you. It will make you look poor and therefore incompetent in the long run.