Impervious.

My yogurt lid just told me to try new fruity cheerios. Nice try, but I don't give in to peer pressure from no twos bit foilish wrapping material. Plus I get Applejacks, despite their having nothing to do with apples. Course they have nothing to do with jacks either, so...

Update
Dee brought up an interesting point that flew under the DP radar this week. Luckily now I have the time to educate you all. His comment is about the Amazon 30 day price guarantee, a little advertised money saver.

I've actually gotten automatic refunds on pre-ordered items that're just negative credit card charges, but that's not on price drops after they've shipped the item. But this is after you've actually watched the movie and you notice the price went down. Of course who has the time to monitor all the items you've bought? So you head over to refundplease where they track all your items for you and notify by email if one dips below your purchase price. Then you hassle Amazon to get your three dimes back, you cheap bastard.

What I find more interesting about this is the complexity and secrecy of Amazons' operations. Everyone knows they have a recommendation system, heck it was the focus of one of my AI projects in college. But few people know that asymmetric pricing is also a hobby at Amazon. Sure, prices go up and down over time, but you assume they go up and down for everyone. But Amazon experimented with value based pricing as far back a 2000, where they would charge a person that was likely to buy a product (valued it highly) more than a person who wasn't likely to buy it. Sounds like a nice way for a company to make a buck, if they can keep their customers from talking.

And that's what this Tech Dirt article talks about:
Tech Dirt- Citizen Journalism Bites Into Amazon's Attempts At Dynamic Pricing

The interaction and ingenuity of bloggers, and services like RefundPlease have made the asymmetric flow of information very hard for amazon to maintain. So they've had to resort to other price hike tricks like increasing the cost of items that remain in your shopping cart for a while. Its basically about trying to feel out the market value of an item at the individual level. Which sounds very cool until you realize that you're the individual and its bad for your wallet. So we undertake this kind of warfare, Amazon developing new pricing technologies and citizens developing new price matching schemes. But hey, that's why "the American government is the best government."