There are plenty of options and the price will vary.
First, the triggering system. You could go with E-bay triggers...something like
THIS, or
THIS. With that 2nd one, you would need some sort of hot shoe adapter, or flash unit that have the right socket for the plug.
I have one like the first one, and it works fairly well but not really well. It doesn't fire every time and lately, it's been triggering the flash twice.
For either set up, you would need one transmitter and two receivers.
A better, but way more expensive option would be Pocket Wizards. Their units are 'transceivers'...so they can be used as receivers or transmitters. They can also be used to trigger the camera remotely. They are reliable but rather expensive. Somewhere around $200 each, I think...and you would need three.
You could use optical triggers like
THIS. They fire the flash when another flash is fired in the area. You would need one flash to fire though. It could be the built-in flash or a hotshoe flash on your camera. You could combine this with the radio trigger and have one flash triggered with the radio slave and the other one triggered optically.
The third option would be to use Canon's IR wireless technology. You have a 430 already, which can be a slave, so you would need another slave and a master to go on the camera. The 580 can be either a master or a slave and the ST-E2 is a master only (no flash). Either way, this is a rather expensive way to go. However, it does allow you to retain E-TTL flash metering and you can set your ratios and control the power off all units from the master. They say that the IR system is good inside, but not all that reliable outdoors where it can't bounce off of walls etc.
For flash units, if you go with the radio or optical triggers...any old flash unit will do. I'd suggest somthing cheap but that has some power. I've heard good things about the
Sunpak 383.