Flask guns for a Nikon camera?

I have a Nikon D3100 and I'm thinking about getting a flash gun as sometimes in poorly lit rooms the in camera flash just isn't good enough. Yet I have no idea what I should be looking for and the difference in all types of flash guns. I want something fairly cheap and really just to give more lighting in situation where I need a flash.

The most economical would be the Nikon SB 400. For the most bang for the buck, the SB600 is one you should consider. The SB600 is no longer made but you can find them refurbished on the Nikon USA website store or on Craigslist.

I wouldn't recommend the SB400 - it doesn't have a bounce/swivel head so no possibility of directional lighting.

It is also TTL (auto flash metering) only - no manual control of flash power.

If budget is an issue & you don't mind learning to light manually (it's not hard) then consider a cheaper manual flash.

I use Yongnuo YN560's (about £50), although I also have Nikon speedlights. As I use them both on manual, I find them interchangeable - whichever I happen to grab first.

The cheapest can go as low as $25 but they are fully manual and you have to know how to adjust your camera yourself to make good use of it. Without much skill, you are left to TTL mode which does not require any tinkering of the flash or camera at all. It will cost you though. My advice for you is to get the most expensive Nikon flash you can afford that has TTL compatibility with your camera. Bring your camera to the store so that you will be able to test the flash properly. The more expensive the flash, the more powerful it is so judge for yourself how high or low you want to go.

I'd go with a new or refurbished Nikon SB-700 speed light. Its ALLOT easier to use then the old SB-600. New the SB-700 goes for $365. A refurbished SB-700 goes for $280 and lower. I use the SB-700 on my old D70 and my D7000. Its a great flash. You'll learn how to use it quickly. Or you can just leave it in i-TTL mode until you decide to get more creative. The SB-700 will work on you D3100.