Bolivia in overall the poorest country in Latin America - life standard is terrible. But in a way, they want it this way, is what I think - it's a country with very strong indigenous roots and it's usually the indigenous who are considered "poor" in their extremely simple, traditional houses in extreme landscapes living under extreme conditions.
Mentioning you need fertile land - I have travelled a lot in Bolivia. One time, I got a ride with a oil-cargo boat on Mamoré River, which passes through Trinidad and goes all the way up to the border of Brazil where it changes to Rio Madeira in Brazil. Well - I asked the staff on the boat how much it is to buy a land in the area - this is Amazon jungle in the Beni region - and they told me, in fact the land is free, for those who want to work it, but they need to get the people owning the neighbouring lands around yours, to accept you in the community. This shouldn't be all that tricky - all just about negotiations. But what's trickier is being a foreigner wanting to establish something in Bolivia - you probably wouldn't be able to make it in your name, but would have to get an ally in Bolivia, someone you can trust, to help you with this one and have all papers on his/her name.
You could also consider the lands of the Yunga region which is very fertile - there are some extremely poor communities there who need some serious development but buying land there will cost something, next to the Amazon which is free.
Bolivia is an amazing country.
Well travelled pretty much all over Bolivia.