GRAND RAPIDS (WZZM)-- When some local children received bad news about their dad's health, they didn't get angry or depressed; they got busy trying to help.

Justin Johnson recently had knee surgery and he learned on Wednesday that he has developed a blood clot that could endanger his life, but the medication he needs to dissolve that blood clot is expensive: $510...with insurance.

To help pay for his medication, Johnson's two sons, Isaiah and Bryson Johnson, along with their cousin Maddie Lane, began collecting, painting and selling rocks.

The kids apparently have a knack for sales, raising well over $100 during their first three hours selling the rocks this afternoon. The rocks are being sold for $1 each, but if you buy four you get one free.

The young salespersons tell WZZM 13 that they will set up shop for as many days as it takes to raise the money needed to buy their dad's medication.