All mints buy precious metals for their various collector series on forward contract.
For their retail issuing pricing on the PM component of those products, that part of the pricing is made realtive to their forward contract price, and the current PM price at the time of sale, for overall optimum profit.
The retail sale issue price also has other components in it, such as
the cost of manufacture,
packaging costs,
marketing costs,
distribution costs,
taxes, and
profit.
All of these costs have to be recovered in the retail issue price.
In most cases, the volume issued for retail sale is what the mint considers to be the maximum the market will bear, relative to the intended issue price for that issue. The volume for a new issue is judged on feedback on how previous issues have performed under similar conditions.
Sometimes, they get that wrong. This is where a collector with good judgement can invest in a new issue, or in the aftermarket, to his benefit.
I agree with MobOfRoos, if you are strictly into Australian bullion coins.
All of the Mint's costs are sidestepped, by simply buying in the aftermarket on long established issues with long established pricing.
In this sort of case, common sovereigns and 1937 crowns were never issued as collector's pieces, and at a time when mints were not into high powered commercial marketing to collectors.