I thought this was a little odd: thanks to someone here, I found out that Amazon had lowered the price on the Dewalt Planer I bought a couple of weeks ago by about $50. I emailed Amazon, and they cheerfully credited me for the difference between what I paid and the new, lower price.
Today, I got an email about a drill press vise I had ordered. The price has changed and they want me to approve the new, higher price before they send it.
The old price: $27.95.
The new price: $27.97.
They apologized for any disappointment or inconvenience that change may have caused.