What does it cost to dig out a 15x15 crawl space? We want to make our basement bigger and make it a walkout?

we have a partial basement with crawl space which is 15X15. It is big enough to stand in but not quite upright. We want to dig it out and make it a walk out basement in this portion (we would have to terrace and reinforce the outside yard as we are not on a sloping yard)