Off brand camera flashes?

Poor college student looking to get a flash for my camera. Are there any off-brand flashes that would be comparable to say a nikon sb-400? I don't know much about flashes so I figured I'd see if someone knows of a specific one.

I have a Nikon D40.

Added (1). Kinda left out a major detail haha lookin for one that's TTL compatible with this.kind of looking like i'm limited to the SB-600 or 800 for what i'm looking for… Can anyone confirm this though?

I don't know of a specific flash, but different companies make flashes just for Nikon. Don't ever use a older flash as they sometimes have high voltage that will damage your camera. Good flashes will integrate with your camera so the flash and camera can communicate back and forth and control each other.

Buy a good used Nikon SB600. You can find them for less than $200.

* save your pennies for what you need.
* NO generic flash can communicate with your camera
* Determine if you really NEED an external flash. Unless you are shooting a lot of events, you may not really need one

If you want something a more powerful than an SB400 but less expensive than an SB700, the Promaster 7400EDF Flash for Nikon might work okay.
http://www.idahocamera.com/browse.cfm/promaster-7400edf-flash-for-nikon/4, 1224.html

Yongnuo