I got mine at Michaels Art supply- they have a website too and you can get it there. It works REALY well. I painted some of my armor with Kryalon crhome and it looks just like the helmet I painted with regular old metalic aluminum and used rub n buff on. It's fantastic stuff!
I was going to use the black for weathering....Beware at micheals and other like it they seem to only carry silver, gold, and copper. The black i have had to order online this is the best deal site i have found yet...To make it worth while i would buy 2-3 at a time....