Join them. I struck up a deal last night with my main gem market competitor to white list each other. White list is a function where you don't undercut a certain person when you autopost. It will automatically post at the exact same price as them.
This is a viable option in a market dominated by just a couple of people. It ensures that you both get your sales and allows you to actually play the game instead of camping the AH.
It is also an advantage for when you just do not have the time to constantly repost (have a job, life outside of WoW etc.).
I am pretty happy with the deal. I can focus on other WoW related things now and still make my gold.
Win-Win for me (and seemingly everyone involved as the competitor was on his main running heroics instead of camping the AH).