Get the opti from thepartsladi on ebay. I had one that still worked but just threw it out about a month ago (sat in the garage since Feb).
My original lasted 125k and still worked when I pulled it. Any other car it's just like replacing the cap and rotor, don't know why so many people bitch about it. Half the time they misdiagnose and it isn't even the opti. Anyway, partsladi sells genuine delphi units for like 230 shipped.