I've always wondered about the price grouping of countries. What is it about hits from countries in group C, that make them so much less valuable than hits from group A? Is it as simple as people from group A are more likely to speak English and fit the target demographic of the advertisements?
If so, I can't really complain because that is a valid reason, but as it stands 95% of my traffic is from group C so the effort of switching over to a new image host is not really worth it.