The rate of undercutting is silly you only need 1 gil less to be at the top of the list and sell first. There is no reason to do a 50% undercut unless you love giving me extra profit as I buy it and relist it at my price and still have it instantly sell. There is no reason to cause a market to crash by listing stuff at such a huge undercut and start a bidding war.
What they need to do is make the lowest market price be the default price instead of using the vendor price when listing an item. That way they can see hmm this item is 8k maybe i should put it up for more than 2k. That or have the market histrory visible by default instead of having to click a small icon to check it out.