The mine roller looked to be made of three parts: the black core (expensive); the plastic plates (very cheap); and the bamboo poles (cheap as shit).

Provided the weight came mostly from the core and the core never itself got blown up, I'd saw it can clear more than a couple of land mines for the money. Perhaps, a land mine per plastic plate, and if an NGO is paying for Afghani wages, you can roll that baby all day.

Bonus: it creates a relatively "safe" path in its footstep.