Retaining Walls cost ball park estimates
This is a tricky one to price because costs depend on the nature of the soil/rock that needs to be excavated. Below is a rough estimate of the sort of costs you are likely to incur. For a bunch of reasons your proposed site could be difficult, so don't be too surprised if it's more expensive than these idealised cases suggest. In particular costs can spiral as you don't know what's underneath the ground until the tradesperson starts digging! In general there is less variability with estimates of concrete crib walls as they require less excavation than timber walls (which can have as much wall below ground as above!)