Well the GradeMaster is going to be about about $550-$600 if I remember correctly, a Landscape Rake is going to run you about $400. Give or take, and if you have gauge wheels it will be right in line with the GradeMaster price. But the GradeMaster is specifically designed to remove ruts and washboarding from a gravel drive, level it, and move the lose gravel from the edges to the center. With the GradeMaster you make a pass each direction and it pulls the loose side gravel to the center as you travel so you start out on the right side of your drive going from the garage to the road. You then line up at the road on the right side of the drive (which is obviously the opposite side) and pull it back toward the house. The angled blades automatically pull loose gravel to the center.
I know a guy who has used one on a field to make a road and swears it is far better than a regular box blade or any other implement for grooming a gravel or dirt road.
Again, I've never used one, but for a 400' gravel drive, I think I'd seriously look at a GradeMaster instead of a Landscape Rake.