Let me tell you one thing right off, if your thinking of a cheap & easy food plot you mights well not even attempt it. You'll just be wasting your time. But if you truly want a nice food plot, plan on doing it right, and spending a few bucks to do so. Like mentioned first off get a soil test, so you know what your soil will need for lime & fertilizer. That will give you a good idea of its expense. 2nd if your have a deep rooted sod. One thats been tall grass & weeds for yrs & yrs. More than likely your going to have to plow the soil, turning over that thick sod. No atv is capable of doing that. To check your sods thickness simply dig into it with a shovel, and see how deep you have to go before get good dirt minus all the roots. If your sods only few inches than you can probably get away with a disc setup. Which you can often rent from places like Gander Mtn, to tow behind your atv. If its several inches thick, your going to need a tractor.
Also like mentioned you'll also need to weed kill the area.
So you could be looking at couple seasons to get this all done. Preparation is everything to get a good food plot.
1st I'd weed kill, 2nd turn the sod, or disc if can, let the sod rot if thick a season.3rd applyproper amount of lime. If you need several tons, you can buy in bulk cheaper, and have it spread. The lime will then need several months to work down into the soil. I like to spread in late summer- early fall, and let it sit over winter. 4th following spring spread proper amount of fertilizer, re-disc it in. 5th apply seed, and roller pack it into soil. Then watch it grow. Also note you'll need some sort of a mower to cut the plot as well. I use a pull behind bushog w/ my atv.
I hope this helps.