MSA Stealth 4500 - blow out disc issues (can't find anywhere!)

Good afternoon AGN team.

After finding several great deals on eBay for the MSA Stealth H-60 tanks, I had a problem where a tank inadvertently left in the sun blew out it's disc. Great to know, first hand, that the disc served its purpose... however, I've been living the nightmare of finding a supplier that will sell one or two discs. For reference, the item's part # is MSA 482226. Google and Amazon searching finds several companies that purport to sell them, but once you start the process you encounter, "10 minimum," or "$150 minimum" orders, so it's not really practical for my use (I'm not running a tank shop!).

Anyone else have the same problem, finding any reasonable work around solutions? I'm at the point where replacing the entire value to get a more standard blow out system is the only option, but I'd really like to avoid that expense.

Cheers, Dave
FX Maverick shooter