This is actually a good question. I was subscribed Aldara (imiquimod) cream by my dermatologist for several basal cell skin cancers on my chin. I was quoted $657 at Walgreen's for a 24 pk of it. Called the doctor back and told her there was no way I could afford that and asked if she could write the prescription for a smaller amount. She said no, pharmacists don't like to break up the box of it.
I then searched online for it and found pharmacies in Canada who sell it not only at less than two-thirds the price, but also in smaller quantities than the 24 pk box.
I now have to figure out how to judge which of them are scams and which are legit that I can take a chance with.