I had two systems installed last year in WI on my residences. Most buyers now get this test done since it is cheap to do (mail order charcoal tests are only $8 from my county) and lung cancer is serious. Professional digital meter tests run about $150 and are much more accurate adn are usually done in a closed house over 3-7 days. Since you have a system in place the major expense is done. Our systems new were about $500-800. Running the fan is cheap and it's also the only item you'll ever have to replace most likely, which can cost about $200 if you need it done. Some banks will not close until systems get a passing test, so see if there is one on file for when the system was put into service. Probably more than you wanted but hope that helps.
