Cheap, simple photo sensitive "robot"

I am a complete newbie and I’d like to build a very simple robot. I have an engineer in the wings to help me out if I get lost.

My idea is fairly simple

-chassis of wheels https://www.sparkfun.com/products/10825 $14

-aurdwino? Not sure but the cheaper the better could I use https://www.sparkfun.com/products/11114 and if so do I need a separate battery? $9, but $20 if I need a battery

-Photo sensor https://www.sparkfun.com/products/9088 $2

I want to make the robot go straight forward if the photo sensor sees light, preferably a laser light pen.

Could this be done and if so how much would it cost?

Google “photovore” for lots of ideas.

Or Braitenberg vehicle