What do you want to shoot primarily?
I'm assuming because you want the AXMC, you are planning to shoot the magnum calibers.
Do you want to shoot .338LM / .338NM?
Or do you want to shoot .300NM
If neither of those are your choice, and you will only be doing .300WM / .300 PRC and similar, then you can save money by not having the super magnum bolt body and just needing the standard magnum bolt body and the .308 boltface bolt body. (Each boltface body being around $600 to $700)
To shoot .308 you will need the .308 boltface bolt body, (about $600 to $700), the Magazine adapter (about $200) and at least 1 SA magazine (about $100) in addition to whatever barrel you want ($500 on up to about $1100).
How far do you want to shoot & what is your ideal zero distance? That will determine which scope mount you pick based on the amount of elevation you want while still having enough clearance for the front of the scope. (You'll probably need something at least 1.35" or greater depending on the angle as you'll need to have room for the center bell and the front of the scope).
Quite often people on the forum here are selling a complete kit which can be a great deal if you want everything
(but not a good deal if you don't want everything).
For example:
https://www.snipershide.com/shootin...nd-more-9500-00-shipped.6906495/#post-7324912
I would also suggest that once you decide what you want, you give Mile High and EuroOptic BOTH a call up, discuss what deals they have available they can offer you, including discounts based on payment methods, then run the numbers for new vs. used on what you want.
When it comes to used, I'd probably wouldn't have any concerns about a .338LM barrel being shot out as most can't afford the cost of ammunition to do so & on the .308 barrels the round life is usually in the 5000 rounds plus range unless someone is going crazy.
On the .300 WM, .300NM, 6.5CM, .243, 6mm variants and pretty much all the 6.5 calibers just keep in mind that by 2500 rounds the barrel is not going to be at it's prime any more and if someone has been running the barrel hot and hard, you could see it being less accurate than acceptable in 1200 rounds or less. (In the old days of .408 CT, people were ruining barrels with the brass overloaded rounds in less than 200 shots).