Is synthetic a better fill? Most of my hunts won’t be in damp climates but anything can happen on the mountain. I think a 15 bag will be just fine for myself. I sleep hot and will always have my base layers or puffy cloths.
Synthetic is heavier but still retains insulation properties when wet. Down is lighter and compresses smaller. With DWR treated down most people are going with down especially when getting into the lower temps.
I myself went with a quilt for most trips but have a -15 degree bag for the cold ones. The benefit of this setup is I can combine them for really frigid conditions.
I went with a Feathered Friends Flicker 20 degree bag- it's part quilt, part sleeping bag; I opted for a couple of additional ounces of fill and it's a solid 15 degree bag.
I have a 50 degree Apex insulated quilt that has a "poncho" hole in that I use when glassing if my layers and puffy aren't enough. Combined with the above Flicker I have a solid 0 degree system- it's not unusual for mountain weather to be a little off of forecasts.
Pretty flexible setup. The Flicker should be right within your budget, worth a peek.