The big-time sellers of Am_azon use some program/whatever which automatically lowers the price of their wares a cent or so below the lowest price in order to keep their products first in the Used list.
I have an idea. Suppose we all want a lot of cheap books which usually go for high prices. If one of us could offer a book for sale at a ridiculously low price, we'd probably have to wait an hour or so, and I wonder if the programs of the other sellers would automatically lower the prices of their books to beat that ridiculously low price.
Now, they may have set some minimum, so that this may not work--but since many books sell for 0.01 + 3.99 ("shipping"), then there may be some chance where we can lower the prices of books going for $10 or maybe even more. (From personal observation, the prices of books up to $90 are ruled by this automated program--whatever it's called. I've kept playing with the price, and it's dropped by $20. I'm debating with myself if I could get it to $10, buy the competitor's book(s), then resale it at a higher price).
What do you think?