Of course my willingness would vary depending on the project, community, features, stability, etc... but there's precedent. I've had no problem donating similar amounts to browser projects in the past, or smaller amounts (+/- $10) to privacy plugins (Adblock, Disconnect).
As a mac user, it's Safari, Chrome, or Firefox. All three are to varying degrees beholden to advertising powers who want my data, and aren't going to challenge the status quo in a major way. That needs to change, and I'd be willing to support that.
Simplifying, 39% of the world's 7.1bn population is using the internet [1]. That's 2.8bn people. Opera, the least popular major browser, has a 1.8% market share [2].
If the $40 browser could match that share, it'd be a $2bn p.a. business.
Why hasn't it happened already? Are we so enamoured with "free" software that this couldn't get off the ground?
[1] http://en.wikipedia.org/wiki/Global_Internet_usage [2] http://www.w3schools.com/browsers/browsers_stats.asp
Microsoft has traditionally been in the business of developing and selling user-centric (as opposed to advertiser-centric) software. Why wouldn't they develop a user-centric browser and sell it like they do the Office products? I'm genuinely wondering. Would it be hated by developers as it'd limit their earning opportunities?
Opera's market share has been both increasing and decreasing over the last few years[1] but it looks like it is taking market share from IE users and more people are switching to chrome. So I would predict Opera's share would go down in the future.
The big questions for me, would then be: What am I getting from a browser that I pay for over a free one? Can I get the same features out of plugins for a more widely adopted (and hence better supported or developed for) browser?
Microsoft is really business and student oriented with the majority of their products. A browser only matches part of their design goals. They want people to keep paying for their OS and don't want products to migrate to the web where they have to compete with Google (Though they already have to do this to some extent).
Don't get me wrong, I would be personally interested in something like this but don't believe that many people outside of developers (and people doing criminal things whether moral or not) would be.
Not sure what you mean with the last point/question. The market share would be decidedly small, it likely wouldn't be developed for (unless it used a major library like webkit) and most business people wouldn't notice much difference in their ad-based revenue from such a small market share.
Sexual orientation? Medical records? 24/7 location tracker? Banking status? Purchase records? All private correspondence? Check all, and you get a nice fast browser in the phone with integrated e-wallet, e-medical, e-dating, and email.
When you ask how much someone is willing to pay for their privacy, we are comparing a product with uncertain hidden cost vs informed priced products. The result will always end up the same: you get lemons until the information asymmetry is solved.