What is "cost"
What is "cost." There are a lot of considerations in setting prices for a service. The Astrologer has both direct and indirect costs. Direct costs would include an hour or so of preparation (running a few charts, making notes), one to two hours for the reading and the questions and any follow-on chart readings (solar returns, progressions, synastry). Indirect costs might consist of paying for the reading space (office or part of a home), software purchases and updates, seminars and books/subscriptions, advertising.
So, your Astrologer has to also live between his readings. If he is a "full time" professional then the proceeds from all of his readings and appearances has to pay all of his expenses for the year. If he is a "part time" professional than he still has to pay for his costs plus make something for his "time" in service. What would you suggest is reasonable pay? -- $20 per hour for all his skills and insights is a bargain and three hours of time adds up to $60. Add to this his indirect expenses and it would seem that $100 is reasonable.
It isn't easy being a full time astrologer unless you have a lot of service that you can provide and support -- radio shows, seminars, presentations to social groups, psychic fairs, newspaper columns, book and magazine writing, lessons, and readings. Dave