Spend the money on the frame, without getting suckered into exotica or something produced by an "artiste" would be my advice chuck. Many of the components will be consumables. And lots of pricey components offer little but gramsaving, in my opinion, and may well be less durable. A good frame will last you the rest of your life - if you get into this lark the componentry can be changed/tweaked later. Often at little cost.
Ebay is your friend.
My opnion only but i would also go for steel. Aluminium isn't necessarily lighter, or at least in any meaningful way.
I think the way I’ve seen bikes sold in L.A. is the more expensive the frame, the more expensive the rest of the bike. So partly I will be limited by what stores carry.
But looking at aluminum vs carbon, big dip in price and the weight is close. I didn’t look at steel because I assume these are lower end bikes and there is a difference in quality of the components (I had an inexpensive steel bike along the way).
But it seems to me that a good aluminum frame will be great value - IF I can find a bike that meets the key fit criteria, including wider tires.
I take your point about consumables and changing these over time. I also know I want the system to work well under stress. So I don’t know what’s solid and what’s ‘exotica.’
The other thing you mention that really strikes me is weight savings gets expensive when the delta in bike weight is less than a kg overall. My body weight will fluctuate that much (up and down) depending on how much bread I eat ! So light is good but lightest isn’t worth it to me.
PS: only one more day on our 7 day Camino walk. Today was 23 km. It is so much fun to do this with my wife. We are both tired, our feet are tired, but we will be sad when the walk ends. Walking thru rolling hills of varying kinds of forests is simply wonderful.