An excellent Ha'aretz article detailing the history of boycott movements worldwide, including Mussolini's Italy, Cuba, Iran, Israel, Palestine, and South Africa. By and large, the verdict seems to be an outsized faith in the ability of boycotts to contribute to positive change based on the single example of South Africa. In the context of Italy, Cuba, Iran, North Korea, and for that matter Israel (which, lest we forget, is being faced with a comprehensive Arab boycott), boycott policies have ranged from simply ineffective to outright counterproductive.
Incidentally, this I think is one of the reasons why I'm increasingly skeptical of the boycott of Gaza. Part of the goal is to deprive the Hamas regime of materials it can use to enact terrorist policies, and the boycott probably is reasonably good at that. But part of the justification is to try and signal to the local Palestinians that they need to change their government and policies, and I'm very skeptical it will have that effect, when typically such boycott policies tend to re-entrench extremist elements and allow them to blame all their problems on the boycotting outsiders. (There's also a punitive rationale for boycotts, but while I believe moral wrongdoing is a necessary condition for justifying a boycott, I don't believe it is by itself sufficient). More importantly, the efficacy of a policy of boycott and isolation becomes effectively unfalsifiable: If it results in positive change by Hamas, then great, it succeeds (though that raises the question of where the line is between "it's working, keep up the pressure" and "it worked, time to reengage"), but if it cause retrenchment, instead of signaling the policy is a failure, it tends to be taken as an even stronger sign that we can't talk with such a radical regime. It's difficult for me to say a way out of that muck.