I don't want to clean anything with it.
I just want to be overwhelmed with inexpensive suds or foam.
I want to make a foam for a horticulture experiment.
How much will overwhelm you? Dish soap makes a lot of suds, bubble bath, and the foaming hand soaps/Dawn Direct Foam make a lot of foam.
Do you need the bubbles to stick around? If not, a gallon of vinegar and a big box of baking soda will give you a lot of foam (great for a volcano effect), but the don't last long.
Longer lasting... Dawn dishsoap.
If you want the bubbles to be lots and stick around.
Dish soap and a drop of glycerin. Use a stick type hand blender. Use as little water as you can.
If you have harder water you may want to add a little bit of baking soda to soften it but too much will impair your bubble making.