What type of flash trigger works with Nikon SB-600?

I've looked up the Yonguo RF-602 & RF-603 but they are both not compatible with the SB-600. I don't want to for something expensive like the Radio Poppers or Pocket Wizards because I'm just starting off on off-camera flash photography.

What other alternatives are there that are just about below $100?

Your cheapest option that uses the full power of Nikons SpeedLights is going to be the SpeedLight Commander SU-800, but it's no where near your budget!

You have to consider there are remotes and remotes! The only way to stay within your budget is to use a system that replaces the wireless ability of your SB-600, rather than working with it. So your speedlight SB-600 will work with say the Yonguo RF-603, you just will not get the benefits of the Nikon Creative Lighting System (CLS).

*It would be useful to know what camera you are using as some Nikons have CLS capability built into the camera.

I have used the RF-603 with a SB-600…

What is not compatible is that you can't use TTL mode, you must use manual mode. But this is true with any Nikon speedlight.

And even the "cheap" Pocket Wizards are only manual capable as well. If you want to maintain TTL, you need the more expensive Pocket Wizards. You can easily get into $500 or more for those.

I think Pocket Wizards are way overpriced in these days of modern electronics.

It also depends on what camera you have. If you have an advanced amateur camera, such as a D90 or D7000, they come built in with a remote CLS commander that will TTL control a SB-600 off camera, so you don't need a trigger at all.

And if you have an entry level camera such as a D3000, D3100, D5000, D5100, etc., while they do not have a built in remote commander, you can buy a SU-800 for about $250 that will control your SB-600.

While this is not a $100 solution it is cheaper than pocket wizards as you only need the SU-800, and don't need a transmitter and receiver as the SB-600 already has a receiver that will work with the Nikon CLS remote system.

The only issue is that the CLS system is infrared, so it is limited to the flash being about 20ft away, while the pocket wizards are RF and will work with a flash up to 100ft or more away.