Was expanding European interests worth the price that was paid by the Africans?
I think that there are a couple of elements at play here. The first would be that I am not sure a complete answer can be derived to the question because the point of view is essential. In Part III, when Okonkwo comes back to his village, he recognizes the presence of the Europeans. Obviously, for he and his desire to bring back the traditional ways, this is a problem and thus the expansion of European interest was not worth the price. Yet, there are those in the village who directly benefit from working with the Europeans. The Igbo who were installed as proxy judges and magistrates by the Europeans found the expansion worthwhile as it increased their own sense of control and power. In this light, the price that they, as Africans, paid was not as significant as those who were under them. It is Achebe's greatness that he reflects this valence of power in his story. Had Okonkwo returned to his position of power, then I think that he might be reading the expansion of Europeans in a different light. In the end, when examining the impact on indigenous people, some benefited while many others suffered. The price that was paid was seen as too high by some, if they were "the other" in such a process. For others, there was little price to be paid as they sought to be "insiders" in such a political and social configuration.