Turns out they aren't actually that cheap. To get a real EEG from Emotiv, it's $750 just for the device - the $300 version doesn't seem to actually be an EEG, they call it an EPOC, and don't exactly explain what it is, but do mention that it will not give you access to raw EEG data, which is what you need for any sort of legitimate experiment. On top of that, if you want to use the SDK, licensed properly, you need to pay an additional $500 or more. So if you want to play with an EEG and it's API, the minimum price you're really paying is $1250 - far from the $300 mentioned in the article.
In addition, these cheaper consumer EEGs don't produce research-grade data, so while they are good for messing around and experimenting, if you want to get serious, you'll need to upgrade to a more expensive headset.
Quickly browsing the github page of the OS-library it seems like you can extract the raw data from the EPOC which would turn the 300$ one into a decent enough device.
Granted you'd have to write the unfolding algorithm and infrastructure stuff yourself (eventhough I'd guess someone probably has done this already)
Seems like a neat enough toy to add it to my xmas-wishlist. Time to build a light version of the "Ready Player One" cyberworld :P
I used to play poker semiprofessionally and could see this as a very useful device to identify tilt (and shutdown the pokerclient or at least give you an alarm of sorts) or generally wear it while grinding and see what helpful info you can extract when comparing to your hands database.
In addition, these cheaper consumer EEGs don't produce research-grade data, so while they are good for messing around and experimenting, if you want to get serious, you'll need to upgrade to a more expensive headset.