I recently purchased some Spike here in the UK, and it cost nearly 50 quid. But its much better value in the US by the looks. I laid off coffee, tea, diet coke, other stimulants, extra strong mints etc etc and its a very good supplement as far as focussing yourself and getting into the groove. Of the few times I've trained on it, I did not want to go into the gym and sit their sipping water feeling a bit knackered like I usually do, but I got right into it.
EAS used to do a sort of neuro supplement, forget what it was called, but it was very expensive and it worked, this works a little better. If you can afford it, use it.