I don't know about Alphas but Swiftec Anodizes all their aluminum parts. This helps prevent galvonic corrosion. Aircraft don’t use a lot of copper. Mostly Steel, Magnesium, Titanium Zinc and Aluminum take a look at the potentials between metals for yourself-that’s why I added the link.
I didn't mention the name of the manufacture and I will not but when I post the pictures of my shroud tonight- I'll post a picture of the shroud that I got from _____. Then you can compare the two and decide for yourself.
I don't know about you but I'm tired of ordering water cooling supplies and having them show up looking like someone’s little brother made it. $25 may seem a little high but it is a professionally designed and manufactured product. This is not something out of little Johnny's workshop.