swordsswords.com has some pretty sweet 202 stainless steel 10" chucks that I just ordered. They have the holes in them and what sounds like small bells to make (too much d*mn) noise while you are using them. Get passed that though, they make some pretty good chucks for under $20 and that's including shipping.
The 202 stainless isn't aluminum but they are super light (I believe close to the same weight as aluminum chucks) and I am assuming from my limited engineering experience regarding metallurgy of materials, stronger than aluminum. Real shiny and the t-swivel connection is my favorite in my collection.
I would recommend nunchakumall too but I got a quote on some chucks from them. They were a great price for some fancy stainless steel nunchaku but the shipping was $50

Good luck!
