As far as I'm concerned, Portal was worth more than $10 originally. It may not be as long as other games, but I don't rate my games in time wasted, but in the quality of that time. Portal gave me a lot of quality for my time, I was happy, sad, engaged, intrigued, challenged and, at the end, felt genuine enjoyment for the game.
If Portal 2 came out at $45 for the exact same game (lengthwise), I wouldn't think about it as being ripped off, but as rewarding developers who put out an amazing first game (and hopefully an amazing sequel) and finally fully being rewarded for their efforts as they should be. Why should they have to accept anything less than full price for a wonderful game while another study can vomit out Call of Duty:96, which is barely any different than the last one, hardly any longer than Portal, purchased by nearly every single person who owns a device it runs on and never drops below $60?
With my money, I want to reward the studio that puts out Portal, a game that actually engages my mind for once.
I honestly feel that some people will accept to pay ridiculous fees for certain games while nickel and dimeing another studio. These people should start to vote with their wallets and want to support the developers that bring new and fresh ideas to their hobby or enjoy wallowing in the same shit year after year.