This is an extremely valuable essay by Kris Rusch on what is obviously a bugaboo of mine: People naively overpaying for self-publishing services.

Some writers will research their manuscript like crazy, and then they won't spend five minutes on the kind of research needed to keep from getting robbed. Please don't be like that. And please keep in mind that Rusch is both dyslexic and especially dyslexic when it comes to numbers, so however bad at math you believe yourself to be, she is much worse, and yet she is able to comprehend when someone is trying to steal from her. Not everyone is to be trusted, especially not everyone who tells you that they can be trusted.

In short, if a stranger offers you candy, don't get in the van!