Yes, I've seen this firsthand. In some cases, you can buy a Federal Senator's vote for as little as $10k. Using this number on a larger scale, corporations can buy the entire senate for as little as $1 million. The ROI potential on a $1 million investment that nets you complete legislative control in your desired area is just insane.

Granted, these deals are often backended and include a job promise down the road or some similar under-the-table stuff (jobs for relatives, etc), but I'm continually shocked by how cheap our legislators are. You'd think if a legislator knows a corporation is poised to make several billion dollars if a piece of legislation is passed, the legislator should demand a lot higher than $10k.