Whether in person or online the ladies can charge whatever they want. That said whatever a girl brings in on a site like Chaturbate, half goes to the house. If a lady brings in $2,000 during a shift ( easy for the more popular ladies) she gets a grand and the host gets a grand.
Now the cost for private shows? I'm sure the range is bigger than this but I've seen them as cheap as $30 hour ($15 for the lady, $15 for the house I suppose) and as expensive as $2,000 per hour.
Now lets be realistic, most guys on this site gripe about paying $300 hour to see a lady, so I doubt many would shell out $100 per hour for online service. That said, again, many hot friendly ladies online that charge $50 and hour or less. Why? Because they live in a country where cost of living is very cheap. Unfortunately that doesn't matter; it's a global market and ladies have to willing to compete if they want to make money. Or maybe they will get lucky and find the guys willing to pay anything.