/ah on Parkour.
I'd personally suggest starting by completing all of the dropper maps (type /dropper to get to them), as the give a lot of mana for your first completion.
Then, try grinding the "easy" maps for some "easy" mana.
You can also vote for the server (manacube.com/vote) for cubits that you can then sell to other players for mana, but make sure you vote while on another ManaCube subserver; vote keys aren't working on Parkour, but if you vote on, say, KitPvP, you get the keys there and then you can sell the cubits on Parkour.