Just because you can set your Amazon store to automatically change a price based on the current market value does not mean it is the best idea…or at least you should set a ceiling on your product.
Brief: a book that normally retails for ~$35 ends up listed at $23,698,655.93 because of auto incremented price.
Source: http://www.michaeleisen.org/blog/?p=358
I really liked the discussion about using this method to sell something you do not have by having a higher reputation and just buying from the person who actually has the item. Sounds like drop shipping through Amazon.