That's why the whole thing simply depends mostly on the largest slope of the property … ours drops 2 meters over 30 meters, the path to the front door is alone 15 m, etc…. That’s what makes it expensive.
I don’t see anything here that necessarily requires an expensive landscape gardener. We have about the same slope now, which could be terraced in several steps and the slopes planted. Doesn’t require much equipment. Alternatively, something a bit fancier with natural stone blocks and several small walls. Up to about hip height this is doable by a layperson.
And vibrating plates can be found cheaply used, for example. Mine cost 250€, and if I’m ever finished (the book recommendation from is to blame that my garden plan keeps getting more elaborate ;) ), I can resell it for about the same price. Comparable ones at the hardware store cost 90€/week plus rubber mat, so they’re also okay if you do it all at once. The only thing here that will really need heavier machinery is terrain modeling, but then you just have to rent a mini excavator for a few days. With some searching you can rent one for 90€ gross per day.
Sure, a 15m path requires material, but you have that even without a landscape gardener. And the material for a 5m path doesn’t cost that much more if you don’t go overboard on materials. That’s rather the problem when I look around here in the forum. Expansive terraces are made with 1.20x1.20 tiles from expensive materials, which of course then calls for a specialist. And then 2m walls are planned right against the house or the terrain is forced into shape with L stones (which due to their weight can only be moved with a digger). That obviously then costs a lot of money.