I have a custom 7mm Rem Mag. I spent a year sourcing parts and then took all of the parts and pieces to my gunsmith who did all of the real work. Here is the parts list.
Factory Remington 700 magnum receiver and bolt. $550
AG Composites Sportsman carbon fiber stock $720
Douglas 24" magnum contour .700 at muzzle $450
Factory Remington 700 bottom metal (hinged floorplate and internal mag) $275
Shrewd muzzle brake $75
Timney 510-v2 2-3.5lb trigger $150
Leupold VX-5 HD 3.5-15x44 CDS Firedot $1000
Leupold steel offset DD mounts and DD rings $90
LRI machine work (fluting and threading barrel and fluting bolt and new bolt knob. $300
Helix gunsmithing m-16 style extractor, Action blueprinting, assembly, bedding and Cerakote $720
Total: $3240 +1090 (scope, rings and bases)
$4330
Expensive. Yes. Worth it. Yes, for a once in a lifetime rifle. Absolutely! This build tool about 1 1/2 years to complete. Spread the pain out as much as possible. The whole rifle with scope weighs just under 8 lbs.
I have a 7wsm that Hells Canyon built for me on a Tikka action. I'm shooting 175 eldx at 3000fps with RL22. I have not tried other bullets yet. It is very accurate and a blast to shoot. It will be my go to when I head out west again.