Here's the numbers:

Frankston: last quarter growth 1.4%, last 12 months 18.7%, last 5 years 50.8% (gross rental yield 4.2%)
Williamstown: last quarter growth -5.4%, last 12 months 8.2%, last 5 years 41.5% (gross rental yield 3.1%)
Newport: last quarter growth 3.9%, last 12 months 21.8%, last 5 years 68.4% (gross rental yield 3.3%)

FYI, 5% is considered a good rental yield.

Sooooooo, based on that, property prices are slowing EXCEPT in those areas that have traditionally been undervalued (ie. inner west springs to mind) so I would wait, save a deposit and see what next quarter brings.

Have you considered Woodend???????? 83% capital growth in the last five years, in the country and an hour to Bendigo or Melbourne CBD. Not that I'm biased or anything