We can and do get some medicines from a local pharmacy. Markup is a pretty individual practice for each vet. Our markup considers the cost involved in keeping medicine on the shelves (not applicable here), record keeping, pill vials, labels, liability involved in prescribing the medication, creating/writing the prescription. Markups for more expensive medication tend to be a smaller multiplier than cheaper medication.
A pretty fair chunk of our income comes from the sale of medications. Often times that income subsidizes other areas (surgery) that are usually under charged.
Internet sales have changed things and will probably have a greater impact in the future. Be prepared to have other charges re-evaluated and charged more appropriately with this chage. Just my perspective.
Doug, DVM