How much is an external flash for a nikon?

I'm just trying to figure out what i can afford for my next camera purchase. I own a nikon d3000, give me price ranges as well as what the flash does for the picture.

Not sure, off hand. Check out nikonusa.com, though, for model numbers. Then based on desire model, check for best pricing at cnet.com or similar online service.

Go to the camera store and ask them.