Arthur Silber, who used to be Ayn Rand’s personal secretary, tells an interesting story about her. You should read the whole thing, but the upshot is that she bought a Russian opera record she craved, in violation of the official Objectivist policy of refusing to buy from the Soviets.
For Arthur the moral is to distinguish between “principles — which are of crucial importance — and rules, which are merely formulaic versions of principles, applied by rote and without the much-needed attention to context, including personal context.” That’s an important moral, but of some other story, not this one. This story tells us that boycotts are silly. The value that anyone gains from a purchase, let alone what Ayn Rand would have gained from this particular purchase, so far outweighs the damage inflicted on the target by refusing to buy, that such policies are impossible to justify by ethical egoism. On the other hand, if you’re a golden-rule Kantian (if nobody bought Soviet then the regime would collapse) or an altruist (my petty purchase doesn’t matter, I’m doing this for the greater good), then boycotts make a lot more sense.
It’s no accident that boycotts are especially popular with the left. They’re passive (the virtue of not doing something), inwardly warming, and utterly useless.