Amazon is down to $399 with 9 used going as low as $299. Now is good time to buy a used one on ebay. there are so many some are going below $300 and at least 1 was buy it now sold for $199.
The current price on Amazon is $489.99. That is the highest I have ever seen the 436 listed. Amazon constantly changes prices for most of their items, so I wouldn't read too much into it.