Pricing on some relatively high value items at Amazon is bizarre. Two related items, A and B. Manufacturer's direct price for A is always significantly less than for B -- B has some additional features. The pages for A and B on Amazon are chaotic. Page refreshes can suddenly show dramatic price changes to far lower prices than list, or back up to list or higher. Different merchants pop onto the pages for A and B with different prices, some shipping through Amazon, some not. Every page refresh might (or might not) show a complete change. Typically when the price suddenly drops it's a single unit availability, and a purchase attempt will fail because somebody else already grabbed it. Then the price goes back up again, typically with another merchant. I failed three times over a day or so to succeed in a purchase at a lower price. Finally this morning I did, and weirdly, at that instant B (which is what I wanted) was actually priced lower than A, the exact opposite of the actual manufacturer prices. Algorithmic pricing setting is extremely problematic but I think I more or less understand it. But what's not clear to me is the way different merchants pop in with a price for a single unit then vanish from the page as soon as it's sold. Hmm.