Hi Alex,
Welcome to permies
What an exciting stage to be in.
There are a lot of variables involved in the earth works costs. The cost per hour of the operator is going to be a lot more in your area than in mine (depressed economically, rural). A good starting place is to find a person experienced in the work you want to accomplish. Maybe there is a fellow permaculturist in the area with the equipment? Somehow establish what the rate is for the machine and operator. Are you planning huge alterations, or thinking more along the lines of swales, infiltration basins and key lines?
Depending on the complexity of the work you want to accomplish, consider how much earth you actually want to move, and how many times. This will involve many variables as well, such as slope of the land and access, and how far you are from where the location of person & the equipment .
Where are you in your
permaculture journey? I don't want to insult you by guessing you are a beginner, asking you if you know what you are doing. I'll just mention one thing people do with
earthworks:
hugel beds. You are in a very dry climate (as am I). It would not be a good idea to make a hugel mound, but you might want to bury the hugel material below ground level, maybe have water from somewhere fed to the buried material.
Being as you are brand new to this site, you may not be aware of the regional resources. Here is a link I hope will take you to your region:
https://permies.com/forums/f-38/southwest-usa
There might be people there who could help with finding experienced operators and cost estimates.
Good luck
Thekla