Its all about what you want/need to fly.
As has been said above. Lots of people place the importance of an aircraft that is well maintained, has lots of avionics kit, not been batterd and abused by countless students abusing it, high on their list of priorities. Others want an aircraft with decent range for touring. Others regularly need 4 seats etc etc. I myself have been considering this very question. I originally wanted an aircraft for touring. I now find myself looking at something along the lines of a pioneer 300...
http://www.pioneeraviation.co.uk, whilst this aircraft, and others like it, may not suit everybody, if I could get a group going around one of these, the monthlies would be good and the hourly rate would be good aswell. If you want cheap flying I think you need to consider aircraft such as the pioneer. Also, it all rests on what you consider cheap.