What car ?
What engine ?
What is leaking exactly and where ?
Couple of the Hyundai engines have multiple expendible part on them..
If you going to replace the cover gasket, you be best served to replace the cover gasket, spark plug tube seals, 1/2 moons.
Price difference should be obvious.. $15, hack job... $60 kit, complete do it all the first time while apart job..