I imagine 45 minutes of your time is worth at least 10% of the cost of a typical airplane ticket, and if you don't get the ticket and want to fly eventually, you have to make at least one additional round trip, so it's an hour and a half of your time.
I'm in Ann Arbor, where the only efficient way to get to DTW is by car, which means bribing a friend (still not free in terms of friend's time), taxi ($50), traditional airport shuttle (~$30-$40), or shorter taxi plus regularly-scheduled airport bus (~$25). All cited costs are one-way, and a one-way trip is at least half an hour.
I'm in Ann Arbor, where the only efficient way to get to DTW is by car, which means bribing a friend (still not free in terms of friend's time), taxi ($50), traditional airport shuttle (~$30-$40), or shorter taxi plus regularly-scheduled airport bus (~$25). All cited costs are one-way, and a one-way trip is at least half an hour.