Is Amazon the only requirement? No price limit?
How cold do you expect it to be overnight on your trip?
The Western Mountaineering Versalite is great for backpacking, rated for 10F. High quality all around. $600
The Klymit 0F rated bag is lower quality but half the price at $300. Worth a look.
The Kelty Cosmic 20F is a commonly recommended 'budget' sleeping bag. Relatively warm for it's weight/size/price.
You could also add a sleeping bag liner to any other sleeping bag. Or a down blanket over top a sleeping bag. I also really like down booties in my sleeping bag for winter trips. Plus layers of course - like wool leggings + long sleeve top, even a down jacket to bed would help.
Obligatory - make sure you have a quality sleeping pad under you. Important for both comfort and insulation. Critical for a warm night.