I'm not sure why this is such a pet peeve of mine, (maybe it's just me) but it bugs me when people underprice ALREADY cheap items. Do they not understand as long as you refreshed your shop most recently you don't need to make the item cheaper it will still show up first.
I kind of just assumed people were trying to bring the price down so they would have more fragmentiser/recycle beast fodder.
I hate when I autoprice and have pages and pages of items that I don't feel like looking through, but then when I check my shop history I see that a rare item sold for like, 1/20th of its value because some asshole undercut everyone by reducing the price by 80%. I try to remember to check all my prices before I submit the autopricer, but sometimes I just don't have time, and end up hoping for the best. It sucks to see a delish item sell for 2 mil, just because 1 person lowered their price to something ridiculous.
People can price their stuff whatever they want, no matter how expensive or cheap it is. There's nothing to get annoyed about. Either wait for the item to sell, buy the item and sell it for a profit, or lower the price on yours. that's how subeta's free market works.