Least expensive Canon flash that is a slave?

I'm looking for another flash. It would be great if I could use my 580 as a master, and then just have the other flash fire. I have a few questions.

1. Does the canon slave system work well? I would be using it for shooting skating, and also some basketball, so could I have them against a wall facing out and they would still fire?

2. If I got another canon flash, I would be able to have a PW on the 580, but I wouldn't need one on the slave right?

3. My original question, what is the least expensive canon flash that can act as a slave? For example, there are an overwhelming amount of 540 ez's used at B&H for about 130. Would these work?

Thanks!
Nick

The cheapest Canon flash that will work with your 580ex is the 420ex. But it does not have manual control like the 430ex, 550ex, or 580ex. That is OK provided you always want to use ETTL and don't plan to ever use it as a optical or radio slave.

The EZ flashes (420ez, 430ez, 540ez) all have manual control but do not have wireless capability like the EX series do. They could be used with an optical or radio trigger, but like any flash used this way, it would only work in manual mode and have no autoflash. (1/1, 1/2, 1/4, 1/8, etc)

1. Does the canon slave system work well? I would be using it for shooting skating, and also some basketball, so could I have them against a wall facing out and they would still fire?

It is a wirless system that uses light pulses to send info and trigger the slave. It works quite well indoors but has mixed results outdoors.

2. If I got another canon flash, I would be able to have a PW on the 580, but I wouldn't need one on the slave right?

No, the Canon master slave does not work with the PW system. You will need one for each.

3. My original question, what is the least expensive canon flash that can act as a slave? For example, there are an overwhelming amount of 540 ez's used at B&H for about 130. Would these work?

No, As said above.

Thanks! I found a 550 for 150, so thats my next flash. Thanks again.

That's a good price!