https://www.fsd.it/shop/fonts/pragmatapro/
Probably the most complete and polished programming font I've seen. If you like Iosevka, you'll love PragmataPro.
I've been spoiled by Iosevka and PragmataPro's narrow characters, so now I can never go back to "normal" programming fonts...
If you're a software engineer, $100 on a font that you look at 8 hours everyday for a living is a no brainer. You'd probably spend $80 on a mouse, $100 on a keyboard, $120 on a good pair of shoes, $1500 on a good mattress, fonts are one of those things. If you like it, there shouldn't be a hesitation for "oh...its just a font, why should I pay for it".
Typefaces are insanely hard to design and optimize. Sometimes, it takes a couple of years to develop one typeface.
This $200 font is not better than this other $0 font, and it has the same aesthetic. And good luck quantifying "better than" given a list of feature checkboxes that are common to all "programming fonts" including Fira Code, Source Code Pro, etc.
One of my favorite fonts is Isoveska which is free.
I would think it would have to be pretty significant, given the licensing and customisability of Iosevka.