A moldboard plow is the old tried and true method for breaking sod. And they'll be the most common, therefore the most economical method.
Some will say kill off that sod with glyphosate (Round-Up), then work the soil with a tiller.
I'd opt for the plow.
A single bottom can be pulled with as little as 10 or 12 HP. (Just not too fast or very deep)
I've always heard that it takes 15 HP per bottom. (minimum)
Keep in mind that plows come in various widths, in addition to the number of bottoms. Common sizes are 12", 14", 16", on up to more "modern" 18" and 20" plows.
Rule of thumb. A plow can work HALF as deep as the width of the bottom (plus or minus an inch or so...) Example.... 16" bottom works well at 8" deep.
As you might expect, the wider plows pull harder. Also, some brands pull harder than others. (Ford, Oliver, and Massey Furguson plows tend to pull easier than a comparable John Deere )
My personal recommendation for a 1 or 2 bottom plow has always been the Ford model 101. Common, easy to find, pulls easy, and parts still plentiful.