Square-Enix could easily solve this problem by introducing minimum prices, because this messes up the games economy. I'm a weaver. miner and botanist and I can sometimes only sell my wares at a big loss. Some people sell stuff that's easily worth 500 to 1000 gil of materials for less than 10 gil. How is this an incentive to go and gather / craft stuff. It doesn't pay, even worse, it costs money to dabble in the Disciples of the Land / Hand.

And buying up all the lower priced items isn't really a solution either. I tried doing that with cotton coifs. I bought all of them that were on offer below 1000 gil. Now I'm stuck with 30 or 40 cotton coifs in my inventory, and a few days later there's 50 more people selling them for 1 to 5 gil.