Also consider that you don't really need to flatten the ENTIRE ground. Only the perimeter really matters. If all your outside walls are blue then they are foundation attached and you can build from them.
You can have uneven lower terrain inside the house and just cover it with flooring. That is what you will wind up doing anyways right?

You can even have a basement. As long as the house in question is not too huge your flooring will not collapse. If it does and you need to go more than 5 floorings away from your initial grounded floor, then you can always prop it up with a pillar as described below if you wanted a basement, or just raise the dirt in one area in the middle to provide stability.

This way you can just run in a line and level ground around the perimeter instead of flattening the entire area.