I did some quick research and it does look like it's a lot harder to buy debt these days than it used to be. Which is a good thing: there were/are a lot of shady characters involved. Anyway, links:

https://proleadbrokersusa.com/cheap-debt-portfolios-for-sale...

https://www.accountsrecovery.net/portfolios-for-sale/

https://www.debttrader.com/buy/

Caveat emptor.