So, this is from the perspective of cheap-ass, backpacking, shooting, technical gear junkie...
For deals, you just gotta let go of the camo everything and wear more traditional colors.
Kijiji - I have Kuiu and Eberlestock packs that I have gotten for about 30% new price in excellent shape. You can get an old Osprey pack for $150 that will be better than any hunting pack under $500, including my Eberlestock, lol.
Value Village, Goodwill, etc... - Brands that I have gotten from here include: North Face, Mountain Hardware, MEC, Kuiu, Arcteryx, Helley Hansen, Carhaart, and even found a pair of First Light pants. This might sound like you will be dressed like a garage sale, but it is anything but. I only hunt in greens, beiges, browns, camo, black, etc... all technical clothing that is suited for multi-day backpacking type hunting.
Any non-hunting backpacking store like Atmosphere, MEC, Altitude Sports, etc... These places all have significant sales that you do not see very often from hunting retailers offering brands like Sitka, Kuiu, First Light, etc...
Costco - Merino socks... they also sometimes have Merino blend undershirts that are awesome.
With all the money you save... you can buy more rifles and better scopes!!!