This may be old news to everyone except me; however, it is too valuable to not mention to anyone that is interested.
Mods- I'm not sure if this is the right section for such a tool but it is pretty cool for helping one find a great deal.
Camel, Camel, Camel is a tool that will help you identify the past price of items on websites like Best Buy and Amazon. It can also be used to email alerts when a price reaches a certain threshold.
For example, if you were looking at Infinity Primus Speakers to purchase you can see their past price vs their current price, their average sale price, and the highest and lowest sales prices. You can also type in your email address and be notified when the price drops to your range (say $275, or you can receive an email any time the price drops by $.01).
I have no affiliation with the site or company and only post this to help people find the best deals possible.