Opti Spark
Most all your local part stores can order or carry them(autozone, advance auto part, napa, etc, etc). You could also check on ebay. I just order a MSD cap and rotor kit, MSD wires and MSD ignition coil for mine hoping that it fixes my problem.
I highly advise against autoparts store Optis. Their cap and rotors are how you say 9 times out of 10 garbage. Get one from a GM parts guy like DAL for $234. Chance it with an Accel or Summit opti for about the same, or Pay over $500 for a dynaspark or MSD and still chance it

