You don't buy it, you either make it or you are gifted it.
It is EASY to make.
To the original poster:
That angry presence was your fear of the other. It was not really anger, it was fear, and the reaction to fear is anger.
So, next time, in a calm environment, that you are very secure in.
right before the hit.
Lookup and say:
I thank you (whoever you are) for whatever experience I am about to have. I know I'll be back, and nothing can harm my body, and I respect what is about to happen too much to worry about my mind. I'll be ok, and I'll learn something.
Really. If you can't say that in all seriousness, out loud, without giggling or being embarrassed, then you might not want to be doing DMT.
But if you can, then you KNOW it'll be all right.
Note: But even with that advice, take precautions. Do not do a movie trip without being aware of the general content of the movie. On the other other hand, if you want an ADVENTURE, take a strong but NOT cross-over hit while watching 5th element, at the opening of the scene of the hand showing up in the lab.
Another great moment is the moment of the rocket launch at the end of Babylon AD. Or the beginning of the ski battle. Or the (you get what I means).
The Matrix lobby attack scene is wild, but i had to turn it off, I could not handle the spinning perspectives.
Also, a threshold dose normally takes 2 strong hits. Have 2 pipes ready and packed, and do NOT use a lighter that continues to burn when dropped. Lean back on a pilow on a couch or bed, do NOT lean forward by a coffee table. Quickly take the 1st hit, and use it as a measuring tool. If a threshold strength has been achieved, you will know it by the taste and initial rush. Not the 1st couple of times, but it will "click". And you will know if you want/need the 2nd pipe for the threshold cross.