Soil cement is a worth looking into. There are many websites that explain it in detail. Your scale will dictate what equipment you can use. For a driveway, you can probably it done with a farm tractor, tiller and renting a compaction machine (Roller). Soil cement is made by mixing cement with soil. It is basically a weak concrete and has about 10% of the strength. But 6-8" of soil cement is enough for a driveway. You basically remove topsoil, do the required grading (slope toward hill if you are going up the side), till soil, spread cement, till and add water, regrade if needed, compact, let it set for a few days. On larger scale you can get bulk cement for a lower price. You will want to a little test area before you go wild.
I have worked with it upgrading county roads to handle large truck traffic. They use about 12" of soil cement and 3" of asphalt. It works well, with only issues arising when the subsurface below it is not very strong (soft Clay, or next to a slope and little berm)
