It seems that the active compound of the vast majority of pre-workouts is caffeine, which can be bought for a fraction of the price or just taken as coffee...
If it makes you work your ass harder in the gym then happy days.
I used to be a huge fan of Ephedrine + caffeine. I had these crazy intense, focused WOs with it (I'm a coffee addict in the first place).
But then ephedrin / ephedra became more and more of a pain to find so I had to drop it. I'm now living in a country where ephedrin is classified in the same category than rec drugs and a handful of pills will get you behind bars for a minimum of 2 years, needless to say I'm not even thinking about getting some.
In the end I find it a positive thing as I started to get "addicted" to be amped while working out, I just felt lethargic if didn't pop them, not very healthy IMO.