I have two boards from PlanetCNC in like-new condition listed on eBay. My CNC fun has been put on hold while I’m in grad school due to not having a space to operate my XCarve 
Reasonable best offers will of course be considered.
From PlanetCNC website:
CNC Controller Board (Mk3/4)
Paid $210 ($133 for board, $77 for license) + S&H
On eBay for $180 with free shipping
Controller Board
Paid $77 +S&H
On eBay for $55 with free shipping
And here’s a link to my CNC build that these circuit boards were used in.
My CNC build