A few months ago I was in the same boat and had to buy an essay to get a good grade.
Not cool.
I used to have a home typing business, and most of my clients were students from the local college and sometimes the universities (some of my clients did me the honor of contacting me after they went on to university, saying they didn't want to trust their papers to anyone else - since I'd been the typist who'd dealt with them for the previous 2-4 years).
On a few occasions I was asked to write original material. One occasion was right in front of the student association secretary - a guy offered me $25 to write his term paper. I told him, "That would get both of us expelled. So no. And even if it didn't, whatever I write is MINE. I don't let anyone else take credit for my words."
Another time it was a guy in the science fiction club on campus - asked me to write his English essay for him. I told him off and said to write it himself, because plagiarism/buying papers would get him kicked out.
There was another client who asked, "Do you guarantee me an A"? I told her no, I couldn't. I said that if her instructor thought her paper was worth an A, that's what she would get. If it wasn't worth an A, she would get whatever the instructor decided. The only thing I guaranteed was that I would do the very best job I possibly could, to ensure her paper was accurate as she'd written it, proofread, and correctly formatted. As it turns out, she was an "A" student and was my client for 3 years.
So I don't have a lot of respect for the underground essay/paper trade.