Well, I got a drop last week, a fairly rare orchestrion roll. It sells infrequently, about one per month. The going rate is ~5 million.
Currently 3 up on my server. No problem.
I list it at 4.999M, undercutting by 1k. Check back. Someone has undercut to 4.7.
I undercut by 1 gil.
Same person undercuts me by another 200k. This continues until the price drops to 3M in the space of 8 hours.
Why do people feel the need to undercut by so much?
If the item moved any faster, I would buy it up and gain control of the market.