They must, however, be done properly by a professional that understands the challenges of a basement remodel. From egress, to moisture, to insulation, the right choices need to be made, or you could end up spending a lot of money on a project that is uncomfortable and potentially unhealthy.
If you are looking to add living space and value to your home, basements are your best value. While each basement has its own conditions and challenges, in general it is far more cost effective to convert a basement into living space than it is to build new space. Whether it is a rec room for the kids, a theater for family movies, an extra bedroom for guests or even an income producing apartment, basements are great investments.