Just saw this article posted from the New York Times :
Why Your Pharmacist Can't Tell You That $20 Prescription Could Cost Only $8 (paywall)
The article exposes a practice by which pharmacists are gagged from telling customers that drugs would be cheaper with cash purchases. Now I don't know how common those gag orders really are. But it seems they happen. It also highlights the fact that cash prices for drugs may be less than the negotiated insurance rate.
In any case, the take away here for me is that if you're buying a drug at a pharmacist then you should ask them what the cash price is.
--This article may contain referral links which pay this site a commission for purchases made at the sites.