If you have the means to load and source correct components I would certainly load your own. Brass for the 450 currently I have not seen any instock. Would like to resupply my stash when it comes available again. Reloader 15 has dried up and if I understand correctly Alliant is no longer producing propellants for the consumer market anymore. I'm currently doing some load workup on Varget in a couple double rifle calibers as my stash of RL15 is dialed in for 5 other doubles of mine and want to save it for those. If Varget does not work out we have imcoming some RL 15.5 we will try. Of course you can use IMR or H4831 they just come with a good bit more recoil IMO.
Keep in mind this is coming from someone who almost likes loading and dialing in rifles as much as I like to hunt with them.