For a house at ~$800k, this batch of suburbs seems to be the way to go...
epping, nsw 2121; Pennant Hills, NSW 2120; West Pennant Hills, NSW 2125; Westleigh, NSW 2120; Cherrybrook, NSW 2126;
Some of the others you mentioned are well in the $1M+ range. Even then, West Pennant Hills may be out...