I have a Sierra Designs "0" rated polarguard 3-D bag that I use for such hunts. It works well. I think you should go no higher than 20 degrees and that may be too light on some cold nights. I think that the next bag I buy will be a down one though. Polarguard is great insulation that keeps you warm even if it gets wet (unlike down), however, you have to be VERY careful to keep it UNCOMPRESSED 99% of the time. If you forget and leave it in the stuff sack for a week several times, it tends to lose its loft. Down will bounce back. So you still have the problem of down getting wet. The newer models have a DWR finish that should shed some water, although they are not waterproof. You could carry it in a water proof bag for transit. They also make goretex type models, but they are REAL proud of those price wise.

Remember that this is an investment that will pay dividinds for many years in the future, so you may have to stretch that budget a might. One cold night on the mountain and you would pay any amout of money to be warm, so don't skimp. Two things I won't tolerate on a hunt: Sleeping cold and wearing cheap boots. Been there, done that and spent some miserable time in the mountains.

I have found several good deals on places like campmor.com. These are usually "seconds" due to stitching variations, etc, but I have never had a problem with anything I have bought from them.

Buy quality, and you should be set for the next 10 years at least.