Also sometimes it's so cheap that... well, why even bother waiting? If that game's on sale for 2 dollars and you want it, what good is waiting going to do you? Hope you can get it in a bundle or something?
It's hilarious how some people get their trousers in a bunch over the price sometimes.
I have some simple rules:
1) If you are paying full price, know what you are paying for. Also, play it ASAP. (This is always funny when someone preorders it, doesn't play it then complains when it goes on sale months even weeks after sitting in their backlog ... really?)
2) If it's 75% off already on the first day of a sale but not featured it's usually as low as it'll go (unless it's Trine or something)
3) If it's a sale, anything I bought at 7.50$ or higher means
you should download and play it as soon as you can (I broke this rule a couple of times)
4) If it's a sale, anything at 4.99$ or less will sit in my backlog for a rainy, rainy day (which might explain why my backlog is also most of my GoG.com collection)