I've been taking Tussin and Mucus Relief, which are both just guaifenesin in the most generic form. I got them both from Walmart, and they were only $0.88 each. You really don't need to spend the money on brand named products here, as long as it's guaifenesin. I got both the tablets and the syrup in case one worked better than the other... and in all reality neither of them do anything for me at all as I have virtually no CM to begin with. I'm still taking it though just because it makes me feel better
Best of luck