I have a 2005 f150 4wd 5.4 v8 with 110k miles, which means I need to change the spark plugs. The dealership where I (religiously) get oil change says it will cost $500. Is this realistic, and can I do myself? Should I change the wires with the plugs? Can I get it done cheaper elsewhere? I typically quit working on my own cars years ago. Any help is appreciated.