Payment is to the individual Congressman's Office, usually a supply fund.
Offices sell the flags at cost.
You can specify who the flag will be flown for, the date, and what the occasion is. Make your request to the office of the member of Congress who serves you or your recipient. Click on the blue link under where to buy to look up the appropriate office email or mailing address. He stays at home a lot and this is something he would enjoy. Click here to be added to this page.