Business-class in an airplane is always more expensive than economy class. The price difference is usually between $50 to about $3000 depending on the airline, duration of the flight, and if it is an intercontinental or transcontinental flight.
Flying business class gives room for more comfort (extra legroom). You also get a great meal service all through the flight.
With most airlines, people with business class tickets get priority check-in and boarding, so you spend less time in the waiting line at the airport.
Traveling business class also comes with other perks such as access to Wi-Fi, an extra level of privacy, make a special request for food and drinks, and better entertainment.
In summary, the cost of business class ticket vary based on the airline you intend to use, and the duration of the flight.