It is a well known fact that Amazon.com changes there prices dramatically and often, it is a lesser known fact that Amazon.com offers a 30 day “best price guarantee”. In other words, if the price of your the product you purchased decreases within 30 days of the day you bought it, Amazon.com will refund you the difference. All you have to do is ask for it. Timothy Noah of Slate just wrote a piece on this, you can find it here. The piece also mentions a site called refundplease.com where you can keep track of Amazon price drops, I have also used one by Frozen Warrior.
Dell.com is another site that I use often which has wild and crazy pricing, (to put it mildly). While Dell doesn’t actually offer your money back in the case of a price drop, they will give you what they call a “concession coupon”, (which often has no relation to the amount of the price drop), for your troubles. A concession coupon is some amount of “free money” which you can put towards your next purchase at Dell.com. So, if you notice a lower price within 30 days of your purchase date, (even if it is coupon related), call Dell and ask for a refund of the difference. After a bit of holding and perhaps a mini conference with a supervisor, you will probably be pleased to hear a clueless overseas operator offer you a nice concession coupon for x$ off your next purchase.