Beware that some providers are in contracts prohibiting them from taking cash payments if they know a patient is covered by the contracting insurance carrier. I don't know the specifics of the business justification for these terms but they do exist.

I've had providers tell me they'd have been happy to charge me less, making less than their insurance reimbursement, but not have to mess w/ billing my insurance, but they were unable because their contract with my insurer did not allow it.