If you are near a junkyard just about every Neon and Chrysler Sebring has a deck that'll fit. They are't difficult to track down. Chrysler/Dodge sedans that age are not rare in junkyards. Just be sure it has the bigger connector and obviously is the round 1.5 din.
Edit: don't get one with an internal CD changer if the vehicle has been in an accident, the changers are really fragile