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Fun With Amazon Wish Lists II: A neat thing I saw today is a search engine for used computer-related books on Amazon. I love buying stuff from used bookstores, so it's no surprise that UsedPrice is my favorite field of the AWS Bag data structure. In this section I'll present a couple simple ideas for efficiently allocating your money by combining Amazon wish lists (or other lists of desirable ISBNs) with AWS' pricing information. These ideas go beyond the Pocket Wisherman, which is designed to help you finding stuff from your wish list in real-world locations.

In the web services portion of Beginning Python I demonstrate a web service client that goes through an Amazon wish list looking for bargains. A bargain is defined as an item available used through Amazon for some small fraction of its new price.

There are lots of bargains because many people think they can make money selling used books online for a penny and making it up in volume. Actually they think they can make it up by skimming money off the $3.50 shipping surcharge that Amazon charges the buyer. But they might as well be trying to make it up in volume, because $3.50 is not that much when you think of the labor involved in determining the book's condition, doing the data entry, then when someone buys the book finding it, packaging it, and shipping it out. That kind of low wage is usually associated with foolhardy professions like writing the books in the first place.

But people persist in listing books online at sub-yard-sale prices, and even when you tack on $3.50 for shipping you can find lots of good deals on books you wanted to buy anyway. The formula I would use today (slightly different from the one in the book) would be to add the UsedPrice for an item to the shipping cost (assumed $3.50), then consider the item a "bargain" if the total cost is 25% or less of Amazon's OurPrice.

Ideally you would have a script that generated an RSS feed containing all the current bargains on your wish list. I haven't written this useful program yet because my pressing concern right now is slowing down the rate at which I acquire books from my wish list.

Recently I was given an Amazon gift certificate. You can't use gift certificates on used items because you're not really buying from Amazon. The rational way to use them is on things that aren't available used, or that cost just as much used as new. In other words, anti-bargains. Tweak the threshold algorithm and by bargain finder script became an anti-bargain finder.

The anti-bargain finder relies on the assumption that used availability on Amazon is proportional to used availability in the real world. If there were some book that crowded used bookstores in the real world but wasn't being sold used on Amazon at all, it would be falsely flagged as an anti-bargain. This is unlikely to happen because so many of the used listings on Amazon come from real-world used bookstores in the first place.

I think I had another hack idea in this category but I can't remember it at the moment. These are pretty simple ideas but they can save you money.

[Comments] (1) Speaking of used books: We went to Borderlands yesterday as part of our Valencia walk and I ended up with three books. Two of them were from my wishlist but--I don't know why I keep buying the old novelizations of Infocom games when they're guaranteed to be juvenile disappointments. Just because George Effinger wrote one doesn't make them a legitimate art form. But yesterday I bought the Stationfall novelization. I don't know if I could even stand to be in the same room as a Planetfall novelization because the game was so great and the book is bound to be so awful. Well, I say that now, but if I ever actually see it I'll probably end up buying it. I should accrete all six and then purge them by giving them away as a prize for the IF competition.


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