Just put in a bulk order of body wash, as it rarely if ever goes on special and we go through it in our household. It's the only body wash I've tried that doesn't leave my skin super dry afterwards (psoriasis sufferer).
There is a free shipping limit of $150 which is kind of annoying.
By my calcs, 3 2.5L bags of milk wash (enough to cover free shipping) is a 19.82% saving over the 1L bottle, or $49.80.
If it's your first time ordering SMARTMOOVE15 also works.
I stopped buying direct from MooGoo as chemist warehouse stocks it now and is cheaper always, compared to the website. This is without factoring in cashbacks etc from CW that often runs from westpac.
Looking at the body wash, it's $79 for 2.5L which works out to be $31.60 per L before discount, $26.86 after discount.
You can currently order, including the botte on Amazon for $24, or chemist wasehouse has the bottle included for $29. IMHO that's barely worth the effort of having to stock 7+L of product at home. The savings only look substantial because you're comparing to the MooGoo listing price of the milk wash bottles, at $33.50/L including bottle.