if I had to guess I'd assume they're pricing with such a high gap so people who don't know what the market normally looks like will think "omg someone must've mispriced this/this is so cheap compared to the rest! what a steal" And either the price is really just 500g because everyone bought out the cheaper listings or they just expired.
Tangentially I've listed things at different ascending prices before (it looks like you're undercutting yourself on the AH), it's kind of a way to hedge your bets so that if the price floor rises while you aren't paying attention you still get to cash in on it. Not sure how applicable it is in this situation though.