How much to to pour 30 x 40 foundation 6 ft. basement anyone thanks
A 6' basement seems like a waste of money. It gives you only 5' - 8". Going deeper (8' or 9' wall) is only a little extra excavation and some concrete, which is cheap compared to what you get for usable space from a normal basement.
That is unless you are limited by the house height or soil/water.