They have a really easy to find cheap brand called Delysm or Delsym...not sure which way u spell it but it is a orange liquid that is pure DXM...you can but it at Walmart in the section with the niquill. My friends and I have done it several times and one 150 ML bottle has enuff to put u into a 3rd plateau dose. I think its 800mg of pure DXM. It doesnt taste wonderful but its not as bad as some other liquid brands and I have never gotten sick off of it. Peace.