These EEG devices become more affardable as you mentioned, however they have a lot of limitations when it comes to the precession of the test. We used Emotiv epoc for some simple BCI researches, yet more preceise devices are in need for detailed emotional recognition researches.

• While EEG feedback devices are less expensive for one to own, it should not be assumed that therefore they are easier to use correctly. The proper application of neurofeedback devices requires an education foundation that is not intuitive. To illustrate my point, a reduction in the cost of a pair of surgical scalpels, say from $50 to $20, doesn't mean the proper use is, therefore, easier to obtain. A toy manufacturer came out with a lightsaber that glowed red with the child "felt the force". The toy glowed brighter when an electrode on the child's forehead that led to an EEG amplifier detected higher amplitude prefrontal Alpha in the child's brain. Humans will "feel" something when their prefrontal cortex produces greater amplitudes of 8-12 Hz (Alpha). Initially, they are likely to feel relaxed because of the increase in Alpha, a slower brain frequency will innervate the parasympathetic nervous system. While this brain state may be easily "felt" what comes with it is a lowering of higher, more alert, brain frequencies (Beta). A careful study of brain physiology has taught us that some kids will sometimes benefit from an increase in frontal alpha, but most kids will not. In fact, the more a child "plays" with a "toy" like this, the more Alpha their brain will produce. This "toy" is seriously dangerous to the welfare of the child. One of the EEG phenotypes of attention deficit/hyperactivity disorder is characterized by excess frontal Alpha. So, well-meaning parents who purchase this "toy" will likely create a situation that will make it much more difficult for their child to maintain focused attention, in general. The bottom line here is that brains are different. Anyone who says they have a one-size-fits-all approach to brain optimization should be ignored, or better yet, educated. No one would buy a pair of shoes from someone who said their shoe fill fit everyone. The ONLY way one should use ANY brain modulation device is under the guidance of trained individuals who will ALWAYS do a careful assessment before they apply a feedback protocol. If you have a rich friend who buys a Boeing 747 jet aircraft that he never learned how to fly ask you to go with him as he pilots the plane from Los Angeles to New York - my advice is, don't go.

https://www.researchgate.net/publication/338186731_Consumer_grade_EEG_Measuring_Sensors_as_Research_Tools_A_Review

Another article for your consideration.