Its always difficult to have a pre-post being accurate to market price, seeing that it may have been created 24 hours prior.
Most Pre-post markets are created around a book value of 160% as opposed to say TABs 118% & Betfair at approx 105% maybe this is done to allow for possible scratchings.

If a horse is showing as odds-on , one can almost guarantee it will be odds on in the actual market , even then, what part of the odds on figure is accurate.
Same for horses which are 2/1.

I have been informed that the WA TAB has an accurate pre-post market in the lower price range also.
One has to first sign up (free) with a code & pass word to gain access.
They have a strange habit of wiping out the pre-post market once the race starts, so it's not possible to go over any past results.

They dont always cover the Country & Provincial races for the East Coast.

Cheers.

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Cheers.