I’m cheap. Half a teaspoon or so of baking soda in a small glass of water. It is not recommended, however, if there is any reason to suspect a stomach blockage.
Baking soda works better than most anything else for me, and like you, I appreciate the low cost. If I can’t get to baking soda and water, Pepcid Complete is the best thing I’ve ever tried, but I buy it in 100 count bottles at Sam’s for very little.