It may be a desert but people still must do paperwork. This section of Mohave Color lists links to sites hawking office supplies in Northern Arizona.
Staples (*) Press the "Easy" button. Staples provides office supplies. They have stores in Bullhead City, Kingman and Lake Havasu City. This link offers free shipping on most orders over $45.
OfficeMax (Profile) OfficeMax is a leading source of office supplies. They have brick and mortar at 1568 Marina Blvd in Bullhead and will deliver.