You can get a waterproof version of the Cradle Mtn - Lake St Clair (Overland Track) map from the Parks shop
HERE for $14.95.
There's also a LOT of related links on our Wiki
HERE, including a link to the Cradle Mtn - Lake St Clair (Overland Track) map for $9.95 direct from Tasmap (non-waterproof version).
(Our Wiki also has an unfinished track notes page for the Overland Track
here, but there's not much on it at the moment, apart from a Google map.)