These Shimano are a good alternative and cheap.
http://www.performancebike.com/bikes...400034__400034
I have two pairs -- one with SPD cleats and one without. The tread is not a problem and actually provides a little more grab when in toe clips. The are also much narrower than dedicated MTB shoes.
Not bad. If my current MTB shoes ever wear out, I'll look for those or something similar. I wear MTB shoes for cold weather or when I'm riding to a destination where I expect to do significant amount of walking.