Rakesh Kumar is not like most of the street vendors in Old Delhi. The hand-painted sign on his wooden counter, “exchange damaged, old notes,” reveals a different story. He sells money.

For the past 40 years, Kumar has offered customers new banknotes for soiled or damaged ones for a fee that earns him about 100,000 rupees ($1,600) a year. It has also helped him pay for the marriages of his three children.

“We charge commission depending on the condition of the note,” the 58-year-old Kumar said while examining some 1,000-rupee notes nibbled by rats. “Around 30-40 people come to us daily.”

Getting fresh banknotes or using soiled ones can be difficult in India. Shopkeepers and other merchants routinely refuse to accept such notes, while people require loose change and fresh notes for regular use.

This business of notes is livelihood for hundreds in Old Delhi, with vendors offering convenience to customers by charging a fee of up to 20 percent to replace damaged banknotes. A mildly damaged 500 rupee note, for instance, can be exchanged for 480 rupees, while a bundle of crisp, new 10 rupee notes valued at 1,000 rupees is priced at 1,050 rupees.