I don't think it's expensive at all, but it all just depends on what you do with it. I make a living writing code, and I write a GREAT deal of that code in ST2. So when I compare my salary in a given year versus how much it costs to own Sublime Text, it's a no-brainer.
Also, be sure to think about this from the developer's perspective. One person wrote the app (correct me if I'm wrong community). If he has sold 5,000 copies for $60 bucks (I have no idea how many have been sold) then he's made $300,000 in sales. That doesn't mean he's made $300k though. I can't speak for the developer, but I pay taxes that would cut that number down significantly. Then there's healthcare costs, medicare, 401k (and other retirement funds) to think of. Also, don't forget that he's been working on this for years - he may not have made anywhere near that amount of money. I'd be willing to bet that the developer doesn't get paid much at all when all is said and done.
Last thing to keep in mind is that you can use the free version indefinitely. You just have to put up with the popup. That's a small price to pay (no price at all) for a great app.