I always plant 100lbs of oats and 50lbs of peas per acre with 100lbs of 13-13-13. Easton is right about the peas. The deer can't leave them alone long enough for them to mature. But that is why I plant them, they are like ice cream to the deer.
Here is my wife standing in a 4 acre plot I did two years ago with that mixture.
For Three acres the cost will be: $120 oats, $105 peas, $90 fertilizer. So, $315 to plant 3 acres with my mixture.