Darryl Dioso
Darryl Dioso reviewedLuna DisplayHardware that turns the iPad into a wireless second display
 RecommendedPros: 

Second screen without having to buy a monitor.

Cons: 

May be too small.

Is this a one time fee?

Darryl Dioso has never used this product.
Yes, Luna is 1 time fee. It was intentionally made as small as possible... and as sexy as possible so you wouldn't want to lose it!