I know this is late and it's kind of lame to do this now, but I've just been going through my finances and I just ran across when I bought Left4Dead 2. I bought it during a sale back in December of '09, and I paid $37.49. Steam ran a special a few days ago for both Left4Dead and Left4Dead 2 for $6.79 each. Wow. I got it on a good sale -25% off, I believe- and the new price is 82% off what I paid for it, or 87% off it's release price of $50.
I was mad at first because of how much money I had to pay for over someone who would buy it now, but then I remembered all the nights I've spent playing games, all of the fun times I've had including playing games with my cousins that live all over the country, and I'd say it's definitely worth the extra $30.
That's all. By the way, anyone wanna play some L4D/L4D2? I've had a hankering for the last week, and it's always more fun to party up. My Steam ID is on the "Games" page of this blarg.