People who have run an online conference, how much does it cost? I am looking at moving a small online conference for around 200 ppl digital, and quotes from suppliers are all over the place. I'm sure this is because no one knows what good looks like or costs....  So, if you have run one, what are your recommendations for estimating cost?
Clarifications:

A satellite solution is not necessary, though I imagine some participants may lack the internet connections to participate effectively. It might be necessary to send hotspots to such individuals.
All four I know of have cost zero.  However, they have piggybacked off university licenses that the host institution already purchased for teaching classes and some small amount of university IT support, and various organizers may also have chipped in small amounts of personal funds for small items.