I wouldn't participate in any conference that charges me to speak. In your scenario, not only do you provide free labour in preparing content and incur travel e

I wouldn't participate in any conference that charges me to speak. In your scenario, not only do you provide free labour in preparing content and incur travel expenses, they also charge you? Nope. Even if paid by your company, conferences where you pay to speak are inevitably lower quality because the real agenda is advertisement, not content driven. I expect any conference I speak at to provide at least free entry, if not travel expenses. This expectation appears to be the norm in several industries.