Sadly, my response to this is that I am not surprised. I do not believe that Perry was selling his executive order for campaign donations in any sort of a direct way. However, I do believe that the personal and financial connections between Perry and Merck were sufficient to induce Perry to do them a favor so long as he did not think that it would cause him any real problems.
I do not think that our politicians are corrupt enough that their votes (or in this case, executive orders) are literally up for sale. However, I do believe that that politicians can be influenced by personal relationships and by the desire to do favors for people who may one day be able to help them out financially or otherwise. I believe that Perry just didn't really care one way or the other about mandating Gardasil injections. I think that he did his former chief of staff a big favor because of their relationship and because he figured Merck could help him some day.