Rapha, nice but a bit pricey?

I'm off for a months (November) riding in the Colorado mountains, any kit people would consider indispensable for that kind of riding/location/weather? I've got a bunch of Rapha vouchers that need spending and want no excuses for not riding when I'm out there.

I'm in Colorado at the moment, was riding both days last weekend - aero-onesie, sunglasses, lots of water.

However, it's already cold when the sun isn't yet in the sky- I had ice crystals blowing through the cone of light in front of me when riding out pre-dawn.

It is really, really dry out here usually - so focus on layers that lock in the warmth (and that can be stripped off in a hurry on a long climb in the sun) rather than anything aimed more at rain.