$10,000 to agent before book published?

Please keep in mind that this was 2nd possibly 4th, or even 5th, hand information. The friend (I'll call her Friend1) that told me this is a gossip. So I take almost everything she says with a hefty dose of salt (and I don't tell her anything much).

The story was that another friend of ours writes children's books... Or at least books of some kind. An that she had looked into getting them published at one point. The agent wanted $10,000 to be payed to them before they even stared shopping the book(s) around, or possibly before even looking at the books... The way that Friend1 phrased it wasn't clear.

I'm not going to ask the other friend who supposedly writes for the full story, as I don't know her well enough. I wanted to check my understanding of how the process works. I thought that you didn't have to pay an agent up front, and that they got a cut when the book was published? How far off am I?

Thanks for the conformation. She didn't try to get them published because she couldn't afford it (according to Friend1). I'm thankful for it not costing anything until published, because if it cost more than the postage/time I wouldn't be able to submit anything o.o

I think Friend1 was partially trying to discourage me from writing, or at least from talking about it what little I do around her. She also said something about writing books not being a good business to be in, I think she found the idea distasteful. *shrugs*