My Fender Tex Spec's and Jerry Donahue SD Tele bridge pus BOTH have BRASS. I think that is traditional too.
Couple of things:
1) Is the Dimarzio brand single coil cover necessary? I see that they are roughly three times the price of my usual dealer....
2) It seems that The Magnet Source will now deal only in orders of 50 dollars or more.... at $0.40/magnet, I'm looking at 125 magnets. Yowza.
3) In my tearing apart what appears to be a non F-spaced Super Distortion (DP100), it looks like I could simply recreate these pups via my little winding contraption!

It seems that I could just jam some regular humbucker bobbins inside a cover with a ceramic magnet and brass plate and I'd be there, at a cost of roughly $7 per pup. It *seems* like the dimarzio I had my hands on was using 42 AWG poly, but I only have formvar and plain enamel. I also noticed that the windings were top-heavy, in the sense that there were more windings towards the "top" of the pup... it seems to me that I'm going to have a few long nights in front of me full of tinkering!