Well I went through my systems for Melb Cup.

They have a 90% strike rate within the selections.

They only came up with 3 selections this year :

The United States
Our Ivanhoe
Hartnell

On top of this I will throw in 2 selections to cover those which the market rates well :

Fame Game
Max Dynamite

Those are the 5 selections if staked to return $100 then :

The United States $5
Our Ivanhoe $4
Hartnell $3

Total : $12 to win $100

but with these:
Fame Game $25
Max Dynamite $8

$45 to win $100.