are very good at making quality burgees, but I would suspect the sell the same Ensign that everyone does... I checked their web site and found that a 3' x 5' US Ensign ran for $95.
The same flag, in material of your choosing was available at American Flag
for between $28 and $37...
Waypoint in Oakland, California
has flags, software
and much more.
They do mail order as well....
Waypoint Web Site