The only stipulation to this question is that it needs to be land that can be fairly easily developed for a home.
I was reading International Living Magazine, and they had an article about how you can buy an acres of land in Ecuador for $3000 that are close to the beach, and able to be developed. They then went on to say "Versus $6000 or more dollars an acre in the US."
Now, I own some land in Arkansas, and it only cost me $1500 an acre, but it was bought a very long time ago, and they are just now starting to put roads in the area. Until last year there were just gravel paths, and no electricity. I imagine I could sell for $5000 - $10,000 an acre by now.
That said, the $6000 number made me laugh. I live 25 west of Philadelphia, and if you can even find an acre of land, it is $125,000 for an acre. We're in almost a rural area... Still suburbs, but if you go another few miles away, I would call it rural.
What would an acre of land, that can be easily developed, cost where you live?
Look for SINGLE ACRE PRICES.... land becomes much cheaper when bought in larger parcels.