Dear Ron Reimer,
The service fee depends on your length of stay and purpose of entry. There are two fees you are required to pay: The stamping fee (paid directly at Vietnam's airport) + our service fee for the approval letter (paid in advance).
For instance, if you apply for the tourist visa with 1 month single entry, the service fee is 12USD/pax (paid online) and the stamping fee is 25USD/pax (paid in cash at the arrival airport).
Any more querries, please contact us at hotline: 0909 343 525 or email us at firstname.lastname@example.org
Helen Truong (Ms.)