Yes, they try to avoid by any means that people start thinking that its always the same on Amazon. Although - it is, more or less. But that's the case in nearly all shops, really. In supermarkets they do it by putting palettes of something in the corridors with neon colored signs, giving the impressin this is the first and last time in history that this stuff is selling for that super low price. But in fact they always have it on sale for more or less the same price. And yet - it seems to work, again and again.

Well, those offerings on Amazon Marketplace, that ask such preposterous prices for things are really strange. I can't figure out what that would be good for. Another variant is, to ask a reasonable price, but then demand $100 for p&p. Do they really think someone will fall for that? Especially since Amazon guarantees that you can get your money back inside the first 30 days.
But the Amazon Marketplace is the modern version of the Wild West somehow. A lot of people get ripped of there - with more sophisticated methods - and face nasty suprises. I just watched a program on that. A lot of people for example buy stuff in China for very "cheap" prices. In particular, luxury brand items like Gucci sunglasses or Addidas sneakers or D&G handbags and such stuff. Which are all fake, of course. If the customs here find out, you can be happy if they only stuff you good into a bin - if you're unlucky you end up in court with a copyright infringement case, which can cost you thousands.
But something else that many people don't considere is, that VAT has to be paid for goods that were purchased outside the EU (in our case). Thats 19% in Germany - which makes many bargains end up not so cheap anymore. That happened to me once as well, with a watch from Japan.