@UTE042_NZ that looks expensive, especially so if you had to pay someone to do it all .
What, if anything did you use to protect the earth facing side of the retaining wall from moisture?
Short story long: About $4,300 (NZ). Including the digger work and his drilling the 16 x 1.6M deep holes (twice, after half of them collapsed during a huge storm late in February and I had to cancel the ordered concrete, pull the six posts I had in position, redrill and start again).
I did everything else myself. Mixed the concrete for the posts in a rented mixer over two days late May with a neighbour trying to help me lose shovel counts - the cement bags are under the tarp in the before picture, between the 1.75M of builder's mix and the 6M of drainage metal. You can just see the stacked posts behind those. Ended up having to buy an extra ten bags of rapid set post mix to top some off.
All the timber is treated: H5 posts; H4 boards. All cut ends treated with Metalex preservative. Soil will only be touching the top two boards as there is 6 metres of 65mm drainage metal (90% of it surrounded by non woven geotextile fabric) over 110mm punched socked novacoil drainage pipe. There's a 50mm - 75mm bed of metal rammed beneath the drainage pipe which gives a sloping bed below the level of the bottom board. The wall should not remain wet for any length of time.
Once it is all backfilled I have to build a balustrade, to stop drunks and babies from falling over the edge. Already have the timber (another $750 worth) but will have to fork out around $250 for galv. bolts nuts and washers. I suspect I might have that done before the shed guys will brave attempting to get a pump and concrete truck down the damp slope beside my house.