A $10 pack from Wal-Mart has worked fine for me, for years.Its small enough that im not overloaded with pack during warm weather, as it flattens out when bungee'd to my tree stand, yet holds a vest, and heavy shirt or two in addition to all my other gear. If its really cold I bungee jacket/bibs to the tree stand. I am all about K I S S (Keep It Simple Stupid),my pack includes: wallet,headlamp,tiny 1 cell light,GPS,grunt call,monocular,pocket camera,facemask,gloves,hat,bottle of water,snack,butt wipes,thermacell (if needed),2 kitchen garbage bags,25 feet paracord,safety harness.
I wear few clothes going in, and add layers after in stand as I cool off.My paracord pulls my bow,pack,and clothes up after I am stable in my stand, and secures pack at shoulder height by wrapping around trunk. That way anything I need to access is in easy reach, yet out of the way.No need to spend hundreds on a pack, thats nothing more than a bag. I did bone out a mature whitetail last year and carried out in this little pack. I simply returned to truck with stand, than emptied my pack of everything but saw,paracord,knife and the 2 garbage bags. Strung deer up, skinned,boned out meat into bags and into pack. The tree saw took the rack off. It was a load for that little pack, but you leave the bones,hide,hooves behind, so it gets more than you think. Happy hunting!