Grade 4 ignorant

[vilakins]

I've been exchanging e-mails with someone who reads the fiction on my site (yes, it has readers!) and recently he asked me what Dorian meant in the following exchange during Rescue. I have no more idea than he has, or why everyone slowly turns to look at Dorian as if he's just said something very significant.

DORIAN: Everything has its price, Avon. You have to decide whether you want to pay it or not. That's all.
VILA: Well, I don't believe in paying.
DORIAN: You mean you're here by choice?
[everyone looks at Dorian]

Does anyone have any ideas?

That reminded me of another conversation in Volcano.

AVON: Zen was picking up a signal from the ground. It could have been some kind of beam approach detector.
CALLY: You didn't say anything at the time.
AVON: No, I didn't.
CALLY: Why was that?
AVON: Because I wasn't sure.
CALLY: That wasn't the reason, Avon.
AVON: No, it wasn't.
VILA: You gonna let me in on the secret?
AVON: You wouldn't understand it if we did.

Like Vila, I just don't get it. If any of you know what Dorian meant, or what Avon and Cally were talking about, or just have some theories, please enlighten me.