To build a quality vocal booth in your home you'll need to first clean out your closet. Take everything out of the closet including the pole. Wash the walls, sweep and mop the floor making sure everything is clean. Then go out and buy some foam. Instead of spending thousands of dollars on studio foam it would probably be better for you to go to Wall-mart and buy some foam that will be much more affordable. Cut the foam according to the measurements. Do not put it up with duct tape but with small nails because tape isn't going to work. After nailing up your foam go out and buy some carpet to put on the floor of the closet. You can put up some touch lights for some lighting. A reflection filter can also help out your sound by giving it more acoustics.