Same here. I've had a lot of satisfaction shooting with my DLSR + IDAS from the city. Nothing beats a cold night at a dark sky site at new moon, but you can usually count the times you get to do that on two hands.
Highly recommend the IDAS. You do need to continuously tame blues and to a lesser extent greens when processing, but its still not too hard to get nice natural colour in the end. Worth checking out Peter Tan for prices
http://www.tan14.com/gears.htm
No experience with nebula filter sorry. If its cutting many more frequencies than the IDAS I'd be cautious about how much more tricky it might make final colour balancing.