What flash-using sites do you visit that you are willing to pay $50 for?
All of them I'd guess.
I've come to the conclusion that the people who don't want Flash on their iPhones don't like to have fun on the internet.
No videos, no games, no rich sites, no silly flash sites that are fun diversions, etc. Just RSS feeds, message boards and the WSJ I guess ;D . I have no hard evidence to support it but I've extrapolated this from thew majority of anti-flash comments which usually mention removing ads or those Flash sites which are done poorly (bad designers and coders are bad regardless of whether its AS3 or HTML5).
What I've observed places this halfway between opinion and fact.
PS. I'd pay $10 for it.