You can pick up good quality lights with over 2000 lumens output for not a lot of money that run on D cells or lithium ion these days. Avoid the cheap ones on eBay.
www.ledtorchshop.com.au
For astronomy I use an adjustable output torch which can go from 200 lumens to sub 1 lumen and is only two inches long. I find it better than a red light as the super low output does not seem to affect my night vision. It's just enough light to read your watch.
http://www.sunwayman.com/html/products/201203/87.html