Replacing valve seals in an engine can cost around $250.00 to $500.00 and sometimes even as much as $1,000.00 depending on the make and model of the vehicle.
When you replace the valve seals in a vehicle it usually involves disassembling the entire engine until you can reach the valve seals.
On some engines such as Chevy 350 engine it may only require removing the valve covers and valve springs to get to the valve seals.
If you remove the valve springs you might as well replace the valve springs with new ones as well.
So if it's more simple to change the valve seals on your vehicles engine then it will cost less but if it's harder to get to your engines valve seals then it can cost more.
I've replaced valve seals myself on a truck for only the parts which cost around $40.00 and then another $40.00 for the new valve springs.
So in total I spent $80.00 for the valve springs and valve seals.
Well I forgot I did need new valve cover gaskets which was another $20.00 so in total I actually spent $100.00
Then again I took a car into a shop to replace the valve seals and it cost me $500.00 because it required a lot of disassembly of the engine to replace the valve seals.