Engine misfires can be caused by a number of things such as ignition coils that are bad, bad spark plug wires, bad distributor, bad distributor cap and rotor, engine timing problems such as a bad timing belt or timing chain.
And even the ignition control module could be faulty.
If it's something simple such as an ignition coil then it may only cost $100.00 to $200.00 to have a shop fix the misfire and if it's something such as a timing belt or timing chain then the cost could go as high as $500.00 to $1,000.00 depending on what is actually wrong and what it takes to fix the engine misfire.