It's easy to losing a highlighter, Wite-Out, etc. Why not make a combo-tool shaped like a big plus cross? So you have a pen and connected to it at a 90 degree angle is a highlighter. The Wite-Out is also connected. Maybe even attach a one-hole hole-puncher for good luck.
So if I'm writing, I can flip the thing easy in my hand and highlight, correct, etc.
Reward: A sample of it.