First of all you need to establish whether the renovation will be as simple as finishing walls and floors, or as complex as adding extra bedroom with bathroom and a fully functional bar or a kitchenette. The complexity of the project will certainly affect the cost. Another thing to consider is the resale value. Updating your home by converting your basement to a living area will certainly increase the value of your property and make your home more attractive to a prospective buyer. For example, adding the bathroom is the most valuable improvement. According to annual surveys of building contractors and real estate agents adding new bathroom can recoup more than 90% of the cost of construction.
Next obtain few estimates from reputable contractors. When you compare the price make sure that the same items included in the job scope and similar quality material is quoted. Otherwise you can end up with unexpected change orders.
.Your estimate should include: framing, insulation, mechanicals (heating, air-conditioner ducts, electrical, plumbing), drywall, finish carpentry (doors, trims, etc), paint, stain, floors, finishing up (everything that makes your basement ready to for use (light fixture, outlets, etc).