I have a couple military grade 1, barely used, bags I use. These are the newer generation bags. They are not the lightest (4lbs I believe) nor the best but they are cheap and work fine. I have a gortex bivy, 1.5 light tent, and 2 person light. What I found is sleeping in a base layer, a light weight quilt, and my bag, I'm good to go with my small tent. Bivy works well too but I've not used it much. The coldest I've done on a November hunt was down to 10F and I was fine, not waking up all night and being irritated. One thing to keep in mind is a decent pad makes a huge difference for a thermal barrier. So, if you want to spend sub 100 or 300 plus, you have a pile of options. Those high end expensive bags are the ticket if you can justify the expense in budget.