Aside from exchanges, is there a place where people list private token sales.
I am looking to acquire tokens that have little to no volume and have fallen 95-98% since ICO.
you should be gambling with that, but it's your money so good luck with that.
Private token sales is mostly viewed as crowd funding, so I'm not sure I understand what you meant.
AFAIR, you can only buy through p2p, or in exchanges, both centralized and decentralized exchanges, but since you are looking for tokens which is almost worthless, I think DEX is what fits with your needs.
Try to search in, IDEX, Forkdelate, and Etherdelta, I'm just not sure if all these DEX are still existing.