Every time I see this thread title I read "Lost cow" instead of "low cost." I was expecting something else the first time I clicked it.
This probably wouldn't work in Afghanistan, but something really cool is a guy genetically engineered a plant that responds to certain chemical compounds that landmines leach out into the soil. So you spread the seeds out over an area, wait for them to grow, and look for the plants with the different leaves. .
http://www.gizmag.com/go/2568/