Valve Cover Gasket, Plugs, Wires $1,300! (2015 Nissan Murano)

I am getting ready to sell a 2015 Nissan Murano (140K miles) and took it into a local shop to diagnose a wheel sound. They did an inspection and found my valve gasket is leaking on both sides. The quote for gasket, plugs, and wires, is $1,300. This is over a quarter of the cars value. Is that the going rate in southern Ohio?

I DIY a good amount of my car maintenance (brakes, suspension, etc). Is a valve cover gasket hard on this vehicle?