My advice would be to pass on expensive machinery. I have used various devices and feel fortunate that they belonged to other people and I was able to BORROW them. I give them a bad review, generally.
The best foundation is to remember what the dormouse said. Make sure that your brain gets all of its nutrients in optimum quantity and quality. Check out Dharma Singh Khalsa's BRAIN LONGEVITY. Also, despite what someone previously said about detoxification, it is an incredibly important focus.
Then you want to build up your intelligence through use. Find yourself some good creative and lateral thinking processes and work them experimentally until they are a natural way of processing for you. Image Streaming is supposed to increase "IQ" by a point for every 90 minutes that you work it; although I have not really worked with this, so I can not PERSONALLY endorse it.
Save your money.
Telesis Foundation for Applied Memetics
CHAOSMOS: The Product is The Process