Probably not very helpful, but I'll throw it out anyway: A former employer of mine goes through a lot of 4" x 6" and 6" x 8" hardened H13 dies in their manufacturing process (and occasionally up to 8" x 14"). I know from experience that the dies have a certain lifespan, after which they get thrown into a 55-gallon drum and sold as scrap... to someone. I'm not currently feeling the itch to hammer a knife out, I'm happy with material removal for now, but if I ever want to branch out I have a plan - give them a call and see if they'd be willing to sell me a block that has worn out its use to them (anyone can feel free to speak up or DM me if there is a fatal flaw in this totally undeveloped plan... like maybe they aren't legally allowed to sell scrap to Some Dude).
Obviously that's only helpful if you happen to have a similar resource, but maybe do some googling for businesses in your area that might use big hunks of steel for something, and make some calls. You never know. One man's trash is another man's treasure!