Yea, homemade varieties often are the best. I had the chance to play around with the SM ones in the link. Not a big fan - they're big and bulky for my taste, so in that sense a pvc one wouldn't be any different. Plus, I found they're pretty big in terms of the feedneck o-rings (although an adjustable feed as on your black magic would nullify that problem). Chances are you can find the SM ones cheaper, but not by too much.
A copper stock class feed with a little bit of elbow grease and polish would be sick!