Rule of thumb for cable laying is between $20K and $100K per kilometre (0.609 mile) depending on environment. (Besides the actual laying, there's design, permits, landowner agreements, surface restoration, testing, certification, blah blah).

So your friend's parents' $20K gets them a kilometre of dark fibre. Maybe.

Edit to add: point-to-point wireless links might work better, but there again for a reliable wireless repeater you're looking at tens of thousands of dollars minimum in a rural environment. And in Kansas you're going to get bad Fresnel occlusion, so you need really big towers.