while searching for my house (which took 8 months, so i'm not claiming this is easy) i followed a great Instagram account called Landio. they share raw land deals multiple times per day, and i recall seeing random blocks of 25, 50, 100+ acre lots that worked out to $500-1,000 per acre.
there are usually a few challenges with this type of land, however.
after a quick search on Zillow, here's a 40-acre lot for $497 /acre:
big open states like Colorado have the most supply of these type properties.