I would say your best bet now, since no buses run from resorts to TTC any longer, would be to take a bus to MK, then walk to the contemporary or hop on the monorail to the Poly.
If MK is closed, then try walking or taking a boat to the Studios, then take a bus directly to the Contemporary or Poly.
If Studios is closed, then if you don't mind using a day on your park pass or have already been in the parks that day, walk through Epcot to the main entrance, and take the monorail to TTC, then Contemporary or Poly.
If none of the parks are open, then you'll have to take a bus to Downtown Disney, then transfer to a Poly or Contemporary bus.
Also, a taxi should be around $10.
Carol