Let's Make Robots!

Where should I start with wireless robot-to-computer data transmission?

I'm working on a project where my bot collects some information while traversing a grid. I want to send the findings back to my computer wirelessly as the robot is moving. The range is not far (2-5 metres) and I am on a budget (Up to $20 but the lower the better).

The data I need to relay needs only be three sets of three single digit numbers. I could even condense it to be three 3 digit numbers or one 9 digit number I suppose.