For people dont realize is that, those 1g undercut is meaning less if say the people you undercutting have a different city retainer. Buying stuff in limsa from a grid retainer will put a fee on ur purchase, while buying from a limsa retainer is a lot cheaper due to no fee even the price tag is 1g higher. So I usually just switch around a retainer and stay 1g higer than the under cutter. And sometimes if people undercut too aggressively, I sell HQ par his NQ price just for the sake of it that I guarantee 100% HQ rate, so NQ HQ doesn't matter to me.