If your suits feel bad you’re probably not wearing the right suits. They are expensive though, that’s definitely true, so it does reveal some of their preferences.

How much money do I need to get a suit that’s not miserable in 90f+ humid heat where even stepping outside in shorts and a t-shirt has you sweating after a few minutes?

I don't think it's necessarily the suit in that case. As a Florida resident, however, I like my Tommy Bahama suit's breathability but it might not be formal enough for every occasion. There's also some "super breathable" suit that I see being advertised a lot, but I haven't tried one of those.