The average cost for a protein bar can vary depending on the size of the bar, packaging, and source of ingredients. In general, the average cost per bar can range from $1.50 up to around $4 per bar. In general, if a protein bar is mostly made from plant-based ingredients, it will be cheaper than bars that have animal-based ingredients such as meat or milk proteins. Larger pack sizes and subscription options can also help drive down the cost per bar.