Some excellent links provided by the U6th (many thanks).
Campaign finance is an interesting topic and examples can be multipurpose as much of the material links into the Pressure Group topic as well.
This piece from abc profiles the biggest donors to the Republican primary campaigns
While this piece looks at the role of personal wealth- in this case in relation to Huntsman’s campaign to win the Republican nomination.
Finally this piece in the Telegraph profiles Gingrich donor Sheldon Adleson in greater detail