The most cost effective option is the board game Mind Flex. You can get it on Amazon for like $100. Basically, you strap a sensor to your forehead, and it reads the thermal output of your prefrontal cortex. It is attached to a fan that levitates a ball. When you have high activity, the fan spins faster and the ball floats higher. When you have lower activity, the ball lowers. You set up an obstacle course and try to navigate the ball all the way around.
The one I use is legit medical equipment, but it cost like $2,000. It plugs into a laptop with the program loaded on it. Then I watch a new movie, and whenever my brain activity drops too low (IE: what movies are designed to do) the movie pauses until I can bring my levels up. My friend is borrowing it right now, but once I get it back I’ll tell you what brand it is.
I would highly recommend doing it with a trained doctor for the first few times, but I know there are very few of those in the world. Just make sure in the beginning you only do it for a few minutes at a time, and only once a week. If you overdo it, it will give you a headache. As you get used to it, you’ll learn how much you can tolerate, and what it feels like when your brain starts getting tired. I only do 15 minutes once per week. It doesn’t take much at all. It is also most effective first thing in the morning, before you’ve had your morning coffee, but after you’ve washed the oils off your forehead. Caffeine tends to mess with your brain waves and give you wacky readings.