The moral of the story is to shop multiple sites. These sites use different CRS systems, so fare filings and taxes can be computed differently.

Any published fare sold on Expedia, Travelocity, or Orbitz can't be marked up, as the credit card is billed by the airline. Service charges (in the case of Orbitz) or shipping fees (for paper tickets) are imposed on any of the sites, but are disclosed separately.

I would buy on united.com if OS doesn't support E-tickets. United.com is one of the few online sites I know of that sends out paper tickets via regular mail for free, and doesn't force you to pay $15 for unneeded Fedex.