Shop around.

Pricing is set by the seller in most states, or else the $4 drugs would not be available at some stores but not others. Those are only available (as loss leaders) for selected meds, usually in the neighborhood of 350 or so of them. Meijer and Publix offer free antibiotics, for example. There are also states with anti-predatory-pricing legislation, like Colorado doesn't allow selling drugs for less than wholesale cost.

You can check some details here: http://www.ncsl.org/issues-research/...ates-2011.aspx

Also, here's a Snopes article confirming that sellers get to charge whatever they want in many states: http://www.snopes.com/medical/drugs/generic.asp

It looks like BJ's and Costco will generally fill Rx's for non-members but you can't pay by check. You might also be able to get mail-ordered refills cheaper (Medco and the like) but you have to plan ahead for that.

I don't see any mention of AZ on those lists, so I have to assume that you'll end up paying whatever the seller wants to demand. If you phone the pharmacies in your area and ask for a price, you should be able to find the lowest cost. My 150mg 30-day fill of lamotrigine costs under $2 with insurance, and Pomco (my Rx insurer) says the retail cost is under $20.