Im not sure on the cost of coating, but you will be happy with the flowtech headers. I have those in my Fairlanes 289, and didnt have to do any mods at all, just bolt in. They where the first headers that Ive ever owned that went in with no problems.
I dont have the coating on mine. I sanded the headers, then put on black B-B-Q paint on it. It hasnt rusted yet, and is a quick touch up if it does. The bbq paint is durable paint, and very cheap, I couldnt afford the extra 300.Can. for the coating. Just keep on top of the headers, if they start to rust, sand them and re spray them,lol.