Advice on an external flash

[StillFocus]

I have a Nikon D3000 and I'm looking to pick up an external flash unit for it. I'd like to be able to set it up wireless, off-camera. From what I understand this is a bit of an issue as I'll need a unit to act as commander since my camera isn't capable. I was told the sb-900 would be capable of doing this, but I really don't want to spend $500 on this.

What would be an efficient, inexpensive way of accomplishing my goals? Is there an easy way to wirelessly trigger an sb-600 or something similar? Is there an off-brand flash unit that would be cheaper? Any advice is greatly appreciated.

[OsmosisStudios]

You can try waiting for the SB-700 (November), which will be less than the 900 but will still have the commander function. Otherwise you're looking at a SU-800, SB-800 or SB-900 for commander flash.

If you want to do it another way, you can try using optical slaves (which are triggered by the light of another flash. Any other flash) or radio triggers (which are more reliable, but can be tricky with SB units).

[StillFocus]

What makes the radio triggers tricky? Is there a particular one you could suggest? If the article I read is correct, the sb-700 is still going to be in the realm of $400+.

Edit: Alrighty, after a bit more research I'm thinking the sb-600 + a radio trigger is going to be my best bet. Can anybody give me any suggestions on a trigger?