The best starting point for finding out how political finance is being regulated in different countries is this international database from the IDEA Institute. It lets you choose your country and the type of regulation you’re interested in (e.g. ban on foreign campaign contributions?); there’s also a version in Spanish.
A recent OECD survey of political finance regulations in Canada, Chile, Estonia, France, Korea, Mexico, the UK, Brazil and India: (OECD 2015. Financing Democracy: Funding of Political Parties and Election Campaigns and the Risk of Policy Capture. Paris: OECD).