I bought the Lange flashcards pretty much randomly. My pharm strategy is entirely flashcard based-I'm using the Lange cards as a base and adding information as needed. So far, I've found that I've had to add a small factoid or two to about a third of the cards. (for example, the card calls the drug a "dopamine receptor agonist" but the text specifies it's a D2 agonist-worth adding in my opinion.
And I don't know if my class is just ridiculous, but there are only cards for about 2/3 of the drugs covered in my class, so I've had to make quite a few. Some of the missing cards were for obvious stuff-no card for nitrous oxide, or zolpidem, which apparently half of SNDers take (Ambien for the pre-meds)-maybe they figured that you don't need that card. Most of the missing cards were for drugs or drug classes that are no longer first-line drugs (my pharm professor likes for us to learn the 'historical' drugs).
Finally, the cards are numbered and there's a good index.