Baking soda has to rank as the most inexpensive/multifunctional product sold. (I do not bake)
Baking soda; White Vinegar
I buy the least expensive no name brands and the largest quantity I can find and do every drain in the house 2 or three times a year.
Remove hair catcher from drain opening. Dump baking soda into the drain, and pour white vinegar on top of the
baking soda. The object of course, is to get the vinegar into the drain, so aim for the center of the baking soda. Pour vinegar slowly. This will foam up! When the foaming action subsides, add more vinegar, again pouring slowly.
Eventually this will all fall down into the drain and continue cleaning as it goes. (you'll hear it working) slowly add more vinegar until you no longer hear the fizz.
Let it sit for approx half an hour and then run water to flush the pipes through.