Top soil is not cheap around here. I had picked the spot primarily because it was semi-hidden from easy view. We didn't do much ground prep, except to kill off the grass, we put soil on top, in mounds. We scraped them up, and moved them to the new, higher spot.
We have plenty of garden area, plenty. Actually, where it is now, it gets sun over more of the day, and has considerably more room for expansion.
The topsoil here is good, but unfortunately only 2"-4" deep before you hit clay.
Planning a small retention pond. We will scrape the topsoil off and keep it, before digging it out.