I would just ban all cards that have the fact that there's more than one copy / an entire pile of them embedded into their design. The problem is that such a list grows pretty quickly.
You start with the obvious cards like Treasure Map, Fool's Gold, etc.
But you could add Rats where it could be an advantage that there's only one.
How about Magpie then?
And Knights, at least you should be able to get your own Knight to defend! But you can extend this reasoning to every attack card since it's pretty harsh if your opponent gets the only curser and there are no trashers in sight. Attack cards only work if both players can get them. So just ban all attack cards. Okay, without attack cards a lot of Reaction cards look pretty foolish, so let's ban them as well.
What are we left with now? Some harmless villages, but wait, what if your opponent gets a village and you don't? Ban the villages!
In the end, the Black Market deck will only contain Pearl Diver and Scout (if you play legacy mode).
I guess I would just ban all cards (aside from those messing with the setup) that have forced instructions that you know can never be fulfilled, such as "gain an X" or "return this card to the supply":
- Treasure Map
- Fool's Gold
- Transmute
- Page / Peasant
- Rats
- Magpie
- Knights
- Farmer's Market
- Gladiator / Fortune
- Bustling Village
- Temple
- Wild Hunt