Easy job for the 90 to 100 k service. NGK Plugs are the OEM Laser Iridium a set runs under 40$. Tools need 10 mm Socket and rachet, Long extension, 5/8 Plug Socket. Silicone grease for plug wite boot and top connection.
Do it yourself or pay an avg of $50 to $100 per hour. A home every 10 years = 120 hours of maintenance.
The old site is located http://homeskillold.skidome.org/