A lot of conference speakers are able to have their employer pay their way. Since I own my own small company, that is not possible for me and I make it clear on my site that if you want me to speak, you have to pay for my flight, hotel, and other expenses. Unfortunately there are conferences that act as if they have a hard time understanding this.
There are even conferences that stick me with the bill. For a conference in Russia a few years ago, I had to get a visa, which meant around $200 in expense and half a day sitting around the Russian embassy instead of consulting (a lot more than $200 lost). The for-profit company operating that conference cancelled their event (supposedly because of the Icelandic volcano and its effect upon air travel) and stopped responding to emails regarding their reimbursement of what I’d spent for a visa.
More recently a conference in a far-away place asked for me to help to pay for my own flight and lodging. I politely ended the discussion with that conference, explaining that I felt that my appearance would be a financial hardship to the conference and that it would not be fair to either of us to continue.
When I speak at a conference in a far-away place, I am generally losing at least a week of time in which I could be consulting and operating my own business. Between travel, jet-lag, and the speaking day at least 5 business days are used up. So, you can consider that my personal expense for time not spent on work is quite high, even if you pay all of my travel and lodging expenses.
It is also the case that speaking events hardly ever result in consulting employment. So, the opportunity to “network” and publicize my business seems to have very little value.
So, I am doing all of my speaking to promote the causes I am interested in, at significant cost to me even if you reimburse me for my expenses. And it is the rare speaking opportunity indeed that is able to offer an honorarium sufficient to compensate me for my time.