I am not an expert by any stretch of anyone's imagination, having only done Colorado twice. But I've just recently gone through the same process you are going through and I got a whole lot of good advice from a native, so I'll pass on some random thoughts to you on what we experienced in the last two years FWIW. Apologize if this is stuff you already know, hopefully some of it is useful.
On clothes, yeah, it costs, but it could save your life. I had to outfit myself and my two sons, and I am barely middle class. Shop Cabelas sales, but Camo Fire often has good stuff at great prices, you just have to be watching their daily sales. If you call them, they will be super helpful in finding you alternatives that are more affordable.
Layers. Really important to dress in layers that dump moisture quickly, but are warm, light and packable. The last two years in the part of Colorado where we were, were unusually warm for that time of year. So you way be in snow, or you may be in near 70 degree weather, all on the same trip. The day may start cold, get pretty warm and then get cold again. So my gear is built on layering up and down all in the same day. My bottom layer is a thin synthetic or merino (including underwear, very important!), and I add and take away as the day and altitude dictates. Usually carry a tech fleece, some sort of windstopper/dwr layer, and a puffy in the pack.
Rain gear. Get some lightweight stuff, top and bottoms. I am told usually you don't get long precipitation, or that if you do, it's usually snow. But this year, it rained on and off during the day, and then when we dropped an elk in the evening, it thundered and rained for 4 hours straight while we processed it. We had rain tops, but no pants and got soaked from the waist down, so much rain that my boots started filling up. It was also cold and windy, so hypothermia in these conditions is a possibility. Light rain jacket and pants for us going forward. If your pack is not waterproof, get a raincover for it too.
Feet...don't think Pacs are what you want. Good hiking/mountain boots are very very important. Schnees, Crispi, Kenetrek, Lowa, whatever...they key is they all have a different 'fit' for different feet. Buy quality that fits your feet. I can't stress how important this is. Some people like stiff boots, some don't. Depends on your personal needs, but spend some money here regardless. The good thing is that the quality boots can be resoled as they wear out for not much money, so they are not disposable and can be made to last a long time. FYI, plan on getting an aftermarket footbed with your boot. Most manu's assume you'll need something that fits your needs, so they don't provide a very good footbed. But some are good enough out of the box, depends on your foot.
Socks....good merino socks are a must. Wicks moisture, keeps your feet temp stable, keep bacterial growth (stink) at bay. I have worn some of my merinos in Texas in 95 degree weather and also in cold Colorado. My feet stay dry of sweat, which keeps blisters at bay. I have two different weights because my feet run very cold when I sit. So I have both heavyweights and midweights depending on the expected conditions. Both will always work, but hvy's are better on colder days etc. Make sure you fit your boots with your chosen socks.
Good headlamps. Two of them, just in case. Going in before light, going out after light...processing meat in the dark.
Game bags, contractor trash bags and light rope. You may need to hang quarters in trees and come back for them. The trash bags are for when you put it in your pack to keep the blood out.
On electronics....GPS solution, whether on your phone or a handheld...you need something like OnX or whatever that shows public and private land...in some units its all mixed together and it's not posted...but you are responsible. If you use the phone app, you will want a battery recharge at least, and you will probably need to DL the map of your unit before hand, as you are unlikely to have cell service.
And if you don't already have one, a rangefinder. Definitely need that. Extra batteries for everything...cold plays havoc with batteries.
And I highly recommend a bino harness if you don't already have one. You will need quick access to your binos and RF. There are lots of choices depending on your style, I use an AGC, and actually have it setup so I can drop my pack and have what I need for a final approach, as well as basic survival stuff in it. You'll also need optics cleaning stuff (lens pen and Zeiss wipes in our case).
Shooting support: No recommendation here except to think through how you like to shoot and get what you need. Maybe your pack is all you need, maybe you want a bipod, maybe shooting sticks, maybe nothing at all...I don't know, depends on you. But it's definitely something we were glad to have sorted well ahead of time. For camp, good to have some barricade or other protectant wipes should you and your rifle get caught in the rain one day (yep...it happened).
And someone mentioned babywipes...concur, you'll be glad to have these if you are up there for a while.
Other random things...basic first aid kit, firestarter (I use Trioxane tabs) and a lighter (I keep these both in my pack and my AGC), possibly a LW water filtration unit depending on your camp situation...we carry lifestraws just in case, latex gloves are nice to have and throw in a ziplock to gather up any trash you make while up there, and we all carry Leuko tape, a little regular tape, a pen for filling out your tag, and one of those emergency space blankets (super tiny folded up, no weight).
Probably some more stuff we carry that I cannot think of at the moment, but hope that helps a bit!
