They're available from the distributor at around 10¢ each. So $3 goes to the manufacturer and distributor and $4 goes to the pharmacy.

Incidentally, the huge difference between street price and wholesale price is the reason why diversion is a problem. If the drugs were sold at $10/pill but with instant rebates to the recipients of $9.90 then they'd probably be kept very strictly controlled, even without the DEA involved...