Wow, that's a really open ended question. There's so many different variables to take into consideration that can have a huge effect on the value of the land.
You can get 5 acres of desert land with zero improvements for <$10K but the price starts to go up quickly if you have water, good soil, in the vicinity of a town, etc.
Can you give some specifics about the property this is being proposed for? Location, climate, soil type and existing vegetation cover, things like that.
"Instead of Pay It Forward I prefer Plant It Forward" ~Howard Story / "God has cared for these trees, saved them from drought, disease, avalanches, and a thousand tempests and floods. But he cannot save them from fools." ~John Muir
Moist Forest Biom
Extreme temps; -40 C to 40 C
Average temps; -25 C to 25 C
Average yearly precipitation 870 mm, no dry season
Acreage has water/clay, forested with evergreens/deciduous, and pasture
Rural, Agricultural; area population 1,300
3 kl from nearby village
36 kl in any direction from 4 nearby towns
126 kl from major city center
Many hands make light work.
Laughter is the best medicine.