What is a natural substitute for butter in Buffalo wing suce besides butter substitute spreads?

It depends on why you can't use butter. If you are not using butter because you don't happen to have any on hand, I would substitute any good cooking oil.

If you are not using butter because of the dairy, you can boil butter gently on the stove until all of the milk products evaporate or solidify and drop to the bottom of the pan. This is cooked past the "clarified butter" stage, till the solids are just beginning to brown. Remove from heat and let sit till it settles and cools slightly, then pour through a fine strainer into a storage container.

Butter prepared this way is called "ghee". It is pure butter fat and is safe for the lactose- and dairy-intolerant. It tastes delicious, having a concentrated buttery flavor, is soft-solid at room temperature, and does not need to be refrigerated (although it will become liquid in the summer if "room temperature" is very hot). Substitute in identical amounts for butter.