If you've got the time, you can buy a disk for whay you'll pay to have it done. Granted, it will be a small disk, but at least it's something you'll have forever.
I have a 5 ft disk I bought used for $300. I did a two acre pasture that was rutted for growing roses years ago. Perfectly spaced speed bumps. LOL
First I cut all the vegitation down as low as I could get it.
Then I started to disk. At first it looked like nothing was happening, but after a few hours of going around and around, it started to really show.
Small disks dont have the weight of the big farm ones, so you just have to spend more time workig with them.
I spent about a day disking. After awhile it got real boring and uncomfortable.
After resting a few days, I draged a large oak log with cyclone fence wrapped around it over the field. The log breaks down the high spots and the fence smooths it all out.
It only takes a few hours of draging to smooth it all out like a golf course.
I would never use a box blade for this. It's fine for small fixes or maintaining a road, but on a big area, it will only create a bigger mess.
Eddie