Usually those kinds of things are traded in bulk in some (hidden) forums. As stolen credit cards, payment accounts etc are used to commit fraud and steal money, they also want quite some money for the datasets. And you won't get all of the stolen accounts, just some random chunk with an amount of stolen accounts you can afford. So I don't think it'll help you in your situation.
And beware if engaging with such people. They already commit fraud and they might as well rip you off, too. Not deliver anything or whatever. Since you're doing something illegal, too, you can't do anything about that and some people are bound to exploit that. And don't pay them money regardless, or you'll support their business.
And sometimes lists of stolen passwords, accounts also get leaked to the public and they're available via torrent or something. But that's rare, the datasets are old, or one group hacked another and it was an one-off thing to damage their business... Also not what's going to help in your case. If it's still of value, it usually costs money.