Along similar lines, I've noticed that Delta's website gives different results depending on which browser you use. For various reasons I always have a Chrome and Firefox window open and use them interchangeably. This last summer I was searching for tickets to Europe and happened upon different flight availability and pricing results for the exact same searching steps. I repeated this many times and also checked on IE which had yet another set of results.
You need to get off your arse, Max (or if you're always just sitting there doing internet transactions and postings, maybe it's max-arse), and head down to Goodwill for stuff like what you're trying to acquire.
It recycles something that's already consumed resources, and it also puts a random variable into your preconceived notion of what you're building. You also need to get yourself an IP address spoofer and throw a wrench into the MBAs' evil plans of world domination by emptying your wallet.
I remember that years ago, one Amazon started to dabble with dynamic pricing this way, a common advice on the forums was to delete your Amazon cookie to get low price they are trying to hook new customers.
On a few occasions, with other vendors, I've also seen the opposite, where the price was starting out higher, to catch the impulse buyers. Then, if you were thinking about it and going back to check the item out again, they would drop the price a bit to give you some additional incentive to make your mind up.
There are many different pricing tricks employed these days. A lot of people use pricing search engines and just spring for the lowest price. I've noticed with some vendors, that if you follow the link from the price engine, it gives you a price but if you visit the vendor's website directly, you see a higher price.
Another example. For some items, kogan.com.au has a pricing clock, which starts out low (often meaning preordering an item) which then keeps counting up and the price may be $370.04 (and slowly increasing) with a note "Be quick or pay $389.00". At least this is pretty transparent, no under the table tricks.
Of course, dynamic pricing is an age old phenomenon and it can be based on many things. Frequent travellers would be very familiar with situations where certain items or services would have one price for the locals and a higher one for the tourists. In many poor countries, just the fact that you are able to travel, automatically marks you out as a rich person.
I think dynamic pricing started the very first time somebody tried to sell something!
The very worst cases of dynamic pricing were covered in a design publication a few years back, talking about how wonderful the smart vending machines would be, since they could boost the price of a cold drink as the day got hotter. So that when the ambient was much warmer the pop cost a lot more. I would suspect that a machine like that might sometimes suffer from a tube of SuperGlue in the coin slot. Some folks just don't seem to have much of a sense of humor.
I love Amazon, but have gotten bit with "Dynamic Pricing" many times. I just walk away. If more people do this, it will probably result in less sales revenue instead of more. And eventually the powers that set up the pricing rules will get the message.