Slot Car EEG Game

I am working on a project to make a game that will control slot cars based on EEG readings. The speed of the cars will be based on the relaxation state of the persons playing. The participants would put on a head band that reads brain wave levels while they watch the cars and try to maintain the cars on the track. I don't want the head band to require any special pastes, it needs to be easy and quick to put on. I am thinking the best way to do this would be to use a computer which controls the cars and reads the EEG signals, but if it doesn't require a computer that would be good too. I have looked into using a commercial EEG input device but they are all way too expensive. Ideally the total cost of parts for this project should be around the $300 or less level (computer not included) as that is about as much as I can spend. Any suggestions on how to build this with available parts, or circuit designs, or just general block diagrams of the required function, or any other comments to help make this happen would be greatly appreciated.

Thanks

Dan