I am not certain why you absolutely want a ring flash set-up? Ring flash generally produces horrible lighting for macro work, unless you photograph coins or things like that. I used to have the Canon ring flash several years back and it was the worst waste of money I ever spent, but back then I just trusted the seller as I had no experience with photography.
Like Mike mentionned previously, why don't you use your 430 on a bracket and off shoe cord? That would be pretty cheap. Add a softbox (either a DIY Coke Can diffuser like LordV's or I used to use a lumiquest soft box) and concave diffuser (check out Orionmystery's blog) and you will have great lighting, much better then a ring flash.
Again, might depend what you intend to shoot, I only shoot arthropods.
Martin