I found an article discussing a new Light Sport aircraft, the X-Air. This has a list price of $47k, which makes it cheaper than your average new BMW. At this price it even includes a panel-mount radio and good engine instruments, although they don't include a transponder (required if you're going to fly anywhere near a major airport).
Obviously there are some trade-offs in making an aircraft this inexpensive, and the main one they have taken is that it is fabric-covered, and thus not as durable in the long run as an aluminum or composite aircraft. However, it has folding wings and it can fit in a trailer, so you could park it at your house instead of at the airport.
The main thing counting against it is that it's slow, with a cruise speed of only 90mph. But if you're not in a tearing hurry to get somewhere, this seems like it could be a fun aircraft.