Do something about trading price manipulation

I have seen many seller listing items then not responding at all. I suspect they aim to get in front of the actual sellers to trick new players into selling valuable items at low price. Because right after those sellers listed uniques with lower div price, the subsequent sales orders would go down to exalted.

It is the same with in-game currency exchange, there is always a large number order on the last entry you can see on the ratio table, with smaller orders keep pouring in to block the view of the remaining order prices.

Suggestion:
1. Set certain limit with the premium tab sales, such that one needs to pay currency for frequently changing the price.
2. The trading site is a 100% seller market, how about buyer’s market similar to the in-game exchange, where buyer can set price for the item they want to buy to contest seller’s market?