If you think their price are too high, you should offer a competing service at a lower price as obviously you see this as a great profit making opportunity.
Like when Mulcibar Scoria hit 8M, instead of thinking damn these farmers are unreasonable, I make a few extra pops. When price drop to 4M instead of thinking, damn these undercutters, I stock up and wait until price raise again.
It's a pretty good way to make gil, buy when you think the market is oversupplied and sell when the demand is high.
If you think the price is too high and yet you yourself are not willing to provide this service days after boring days for the same price, then you are just a whiner.