The easiest method to reach the spark plugs and remove the rear back of three spark plug wires - is through the front wheel weels.
This requires the front wheels lifted off the ground (the vehicle supported on jack stands) and the front wheels removed. You can more easily reach the remaining three plug wires and spark plugs - using this method.
In addition, it is recommended to replace the plug wires at the same time as changing the spark plugs. Be sure to apply a slight amount of dielectric paste on the interior diameter of the new spark plug boot.
Try these various on-line parts vendors; www.autopartsanything.com; www.partsgeek.com; www.rockauto.com - to list only a few.
In fact, they (RockAuto) lists the plug wire set from around $12.90 and the spark plugs from around $2.80 each for your vehicle.
Spark plugs = AC DELCO part #14 (gap = 0.060") - or it's equivalent
Spark plug wire set = STANDARD MOTOR PRODUCTS part #27689 - or it's equivalent