Those cracks are caused by the rubber material that the spoiler is made of cracking, not the paint itself. I've seen a lot of people paint them flat black with very good results.
I also have 2 spoilers availiable. $40 plus shipping. The one that you would want is currently Bronzit, but it isn't cracked at all. I understand that you are wary of buying online, but you can look me up here and on r3vlimited under the same username. I have never had any problems, and I'm sure we could work something out that would be satisfactory to you.