Large undercuts don't destroy the market unless the demand wasn't there in the first place.
I've had players undercut me in my niche just for things to bounce right back to my standard price.
I've undercut others by large amounts when I wanted to unload something fast and I'm pretty sure the market jumped back to their preferred price once my item was gone.
What destroys markets is oversupply. Why post 10 of the same item when a brief check of the sales history shows only 3 of the item selling each week?
