Start calling landscaping companies or look in the local area Want advertisement paper, for people that own the equipment, that do this kind of work.
A single guy or gal on a Tractor doing the work in a couple of hours. Will be cheaper then what your labor is worth. They can even it out, add the proper additives depending on how your soil is.
Then just either have it Hydro-Seeded or Sod put down. Hydro-Seed will grow faster then just putting down seed and covering with straw. You do have to water it on a regular basis. Otherwise you will still have nothing but dirt for a yard.
Are you talking about little bumps or rolling hills? If it's the usual little bumps that appear in the spring, you could have someone come out after a good hard rain and the ground is really saturated, and roll it to try and smooth it out.