If you're on the leading edge, with the newest and hottest cartridges, you'd best be served by getting into reloading. New calibres tend to be hard to find loaded, with an extremely limited selection, and expensive. 300WSM brass (easily sized to 325), 8mm bullets and components, on the other hand are readily available, varied, and much cheaper.
You can get dies for about the price of a single box of factory ammo, brass will probably run you $25/50... you will probably pay for the price of all the reloading gear and components by the time you've finished off a dozen boxes of ammo