I'll undercut during the levelling process. Not to such an extent that I'd get less money than an npc would pay me for the item. But if it means getting it out of my inventory then I'm good to sell it for cheap. Ideally I'll make a profit, but some people are just greedy. They want massive amounts of gil for something easily crafted. Nope. If its easy to craft then everyone will do it and the price will be shit.