
I don’t think it’d be that high, retail prices on similar hardware to the specs is ~USD$700, including a (crappy) case and a (decent) PSU.
I think Valve could get it to $649 without subsidy.
Just due to not having pay as much for the parts, they’d be getting the cpu+gpu directly from AMD as ‘semi-custom’ parts, so there is no Distributor, wholesaler or retailer profits to bundle in, the GPU is on the main board too, so no extra AIB profits to worry about on the GPU.
DRAM will be a ‘fun’ one due to price fluctuations though.
Really depends on how much profit they want to make.

To add to this-
One of the biggest traps for new linux users since forever has been to jump straight into the deep end- tweaking any and every tunable- then when that inevitably all breaks, blaming Linux and moving back.
For anyone reading- You don’t need Arch as your first distro, you don’t want to on the bleeding edge unless you’re prepared to bleed. You don’t need things like Golden Eggroll Proton or any external launchers.
Just keep it simple to start- Something like Mint, SuSE or plain Fedora with Steam using the built-in Proton.
Bazzite gets… let say ‘advertised’ a lot and it’s got a lot of good ideas - but if you’re coming from Windows I think it’s just too much - it’s an immutable system* with containers for everything. That’s an ocean away from Windows unless you were comfortable with Sandboxie beforehand (if you were, dive right in)
*\the system is read only, you cannot change anything in the default image, ie. imagine if you were never allowed to add files to c:\windows
Edit: For the newbs, an ancient meme- https://www.shlomifish.org/humour/by-others/funroll-loops/Gentoo-is-Rice.html
Maybe they’ll finally sell of GlobalFoundries,