If you would like video of your band in a live setting other than a stationary camera somewhere then the more info I have in advance the better to keep things at the lowest possible price.
The cheapest way to go is one stationary camera on the band provided there is a good place to put it. If you are looking for something to put on youtube then this could be enough. See the links on right menu for samples. I do not have control of the lighting in these places. So when you book your gig you may want to look into this issue.
There are other filming options you may have. From there the quality only goes up for your finished product. With that so does pricing. So you see that a consultation is a must before I can give any definitive prices.