I would check out
www.hagshouse.com and see if you can find a homebrew p41 IR camera. From what I have heard these have been putting out the best results as far as speed, clarity, battery life, and consistency. Plus you can kill the shutter motor for no sound and low flash. IR cameras do still emit a little red flash but w/ homebrews you can lower it to where you feel it is still taking good pics.
I have made a bunch of homebrews and definately prefer these to about anything else for the money.