I did 21000 cy yards of bony material measured in the cut, pushing up an average of about a 5% grade into a deep depression with the longest push of 350' last year with a rented D8T @ $1.14 per cubic yard and cleared roughly $8800 after fuel, rent, and wages @ $30.00 per hour; mobilization was charged separately. This did not include any overhead, insurance, or daily mileage on support vehicle. I did not have to meet any compaction standard.
Rent was $5333.33 per week, fuel usage was 13 gallons per hour, and I worked 66 hours total. The company I rent from charges the weekly rate for up to 44 hours, and then the weekly rate divided by 44 for extra hours.
This economic example will not work for your project however, as the yardage is considerably less. 100' by 100' by 12' is only 4444 cubic yards; add maybe 20% for slopes and contingency and you are still only at 5555 cubic yards. Also, time wise you will bury you compactor with a D8, or spend so much time leveling so your compactor can get over it that the efficiency of the D8 will be wasted. Add to that the cost of mobilizing a D8 vs. a D6 for two days of pushing and I think that the D6 is by far the correct choice for this scale of project.
A D6R rental for a week should be around $3100. Actually your rental rates may be considerably lower as our climate dictates about a 9 month period per year in which most dirt work can take place, so our rental companies must charge more per month to account for the winter season. Your fuel consumption will probably not exceed 7 gallons per hour. Your production rate downhill with an average push of 200' should be at least 150 cubic yards per hour and quite possibly quite a bit more if you stick to slot dozing. The time required to lay out lifts such that your compactor can get over it will probably cut your efficiency by 20 % or more, and the time required to work your slopes around the pad, and finish the pad to grade needs to be considered as well. Also some time to provide drainage around the perimeter of the pad. Compaction of the pad should not be an issue and will likely almost take care of itself during the process. Add a bit of time to lay any part of the pad that is fill in smaller lifts.
Add for insurance, compactor, labor, overhead, support vehicle, mobilization, and profit and you should be able to come up with a good figure.
Your photos look as if it will be easy pushing, but were it me I would add a rock clause into the agreement. If you are likely to encounter a hard material that has to be ripped then that should be factored as well.
Also, there will be some time stripping topsoil to the side and then covering the slopes and fill after the pad is built.
This is just a rough idea, and I hope that it helps. There are many additional factors to be considered such as will you need water to get compaction on the corners of the pad, and do you need to build a driveway/access road to the pad etc. This stuff is just off the top of my head, and I am sure that I have missed some things, but hopefully others will fill in the gaps and this gives you enough information to prepare your proposal. Make sure you address items like topsoil and drainage with the owner so that you know exactly what he or she wants. Often times property owners do not think about the value of saving topsoil, but at least in our part of the country it is crucial to end up with a nice finished product that is ready for the landscapers.
As for your question in regard to what the going rate per cubic yard is, there are far too many variables to throw a number out there.
