I tend to keep a few things in my Amazon shopping cart, either in the 'about to buy' area or 'saved for later.' Occasionally when I go to the cart, I'll get a message that the price of an item has changed (up or down), with the standard blurb that "Items in your cart will always reflect the most recent price displayed on their product detail pages. "

Today, there are 8 of these notices, for 20 total items. (I'm about to make a largish purchase.) Four increases, from $.04 to $1 (on 2 items costing about $14) to almost doubling (from $6.99 to $12.99). Decreases went from $.50 to $5 (this last on a $19.99 item).