Is there an online formguide...?
 

... that has prepost odds the same or similar to those in the Courier Mail formguide? All the ones I found have market odds which I assume is called "Totes"?

You can try tabform.thewest.com.au which is the formguide offered by The West Australian newspaper.

I don't know if they have the same pre-post odds as Courier Mail though.

If you really want The Courier Mail's pre-post prices, but can't get the newspaper, then you can get it online from pressdisplay.com for only US$0.99 per issue. I use them to get The Sportsman for the same price, instead of paying $5 or $7 for it from the newsagent.