Homebrew PCBs

Hello,

I just joined and have been using ferric chloride to photo etch brass 
sheets to make parts for models. This is a quick rundown of how it 
works:
http://picasaweb.google.com/ErieChris333/Etching

I have read about using Sodium Persulfate instead of ferric chloride. I 
heard it was cheaper and worked faster.

Can anyone here give me some insight. Does it really work better 
(faster)? and were can I buy it and learn how to mix it?

Thanks
Chris