How much a ticket will cost for driving without a license as a minor will depend upon your state's laws. Some states have uniform fine amounts while others have a basic fine schedule for infractions such as this however the court over the jurisdiction where you received the citation will determine your fine amount as well as any other penalties that will be assigned to you.
For example in Connecticut according to their laws (CSG 14-36h and PA 05-215) the penalties for operating a vehicle without a license, violating the driving requirements for 16 and 17 year olds, driving when under 16 or violating other licensing provisions vary depending upon if it is your first offense or not.
CT laws state that a first time offense comes with a fine of $75 to $90. Subsequent convictions for this offense can come with penalties that can include up to 30 days in prison and a fine of $250 to $350. This section on Connecticut law also notes that if a person was previously convicted of violating these provisions they can be fined an additional $500 or up to 100 community service hours. Also if 2 previous violations have occurred there will be an additional mandatory 90 days imprisonment.
In some states you will get the prescribed penalty, fine, etc for driving without a license plus an additional monetary amount due to the state. In some states it is called a surcharge while in others it is termed a driver responsibility assessment. For example driving without a license comes with a $100 surcharge in Texas.
Even if you are a teenager with a learner's permit you can get cited for driving without a license if you operate a vehicle against your restrictions. For example Delaware law states that persons who violate the Level One Learner's Permit restrictions are considered as driving without a license which will result in a 2-month suspension for the first offense and a 4-month suspension for subsequent offenses.
If as a minor you are caught driving without a license the person who let you drive their vehicle may also get in trouble depending upon state laws. In many states it is unlawful for any person to cause or knowingly permit any minor under the age of 18 years to drive a motor vehicle upon a highway as an operator, unless the minor has first obtained a license to so drive a motor vehicle.
To find out the fines and other associated penalties for an unlicensed minor driving contact the court in your area or your state's Department of Motor Vehicles.