How about Flashes?

I would say if you are taking band photos you don't want to use flash. I play too and for one it sucks when lights are already in your eyes to have more lights flashing. Two the picture is going to be off looking because the light is different coming from the flash. Get a fast lens. nikon 50mm 1.8g is a great lens and it's fast enough for low light. You can always bump up your ISO if needed and your picture will look a lot better with the stage lights. Here's one of me with natural stage lighting that my guitarists girlfriend took. He's a pro photographer so she used a good lens to take this but that 50 mm will work great and it's only about $220. Or you can pay a little more ant get the 1.4 or faster.  

I agree,

a fast open lens with higher ISO to increase shutter speed is a better idea.  Flash can look horrible if not used correctly.

You can get a 50mm F1.4 for not too much money these days, there are some great ones on ebay.

IMO don't use flash. Since there is already spotlights and other lighting in bar, just use a fast lens. Set your ISO to the highest so there isn't too much noticeable noise, maybe 1600 as the highest and set your aperture to the largest.. 

If you have seen other photographs taken of live bands/music, you will notice that hardly anyone/no one ever uses flash. 

Thanks! You guys have been most helpful. I've seen youtube videos that showed the photographer using flashes and that's why I thought I'd need them. But this seems much easier. And the 50mm has been suggested to me before. I think I will certainly be getting this lens!