Jenae, your answer was a Loooong one, but with little essence!
No games, remember? Thats your promise. The facts about the cost and which brand to buy is not known to me. You can help me there if you want to. You have only mentioned a 100$

and nothing else!
Scientific Facts
We can know a lot about the brain with an eeg-neurofeedback device. And we can really control it. You know, Jenae, whats wrong with your analogy? You said we have access only to the external, when actually we have access to the most internal phenomenon of the brain.
Its the
Mind!
So, we can monitor the waves with an eeg and the inside of the brain with the mind itself. And we can discover what clicks the generation of a particular brainwave. Thats why they call it
feedback. Whatever thought or, emotion or, meditative mood causes a wave, we can feed more of it to the brain with the mind!
Waves:
alpha wave = usually occurs in dreaming. In wakeful state it denotes relaxed mood and contentment. It increases the efficiency of that individual.
Beta wave = nervous tension and anxiety, unhappiness.
Theta wave = usually happens in sleeping state. It may occur in waking state in short bursts... only to denote creative impulses and problem solving insights.
Delta wave = Complete relaxation. It occurs only in Deep Sleep state, where REM stops.
If you can control your brainwaves, you can be like ... ...
Albert Einstein or, Leonardo da Vinci. :D Yay!