I would suggest telling them about white plastic and flat white paint, since its so much cheaper than Mylar, and a simple wood frame, or closet walls ... I have two very good suppliers:

lights, mylar, light setups, all sorts of growing supplies here: http://www.hydroponics.net/items/

and bulbs, fixtures etc. here: http://www.1000bulbs.com/category.ph...ogen&HBX_OU=50