How to get unique maps?

Noob question here but how do you get unique maps to drop? Its like all other maps where you do the one that is connected to it right?

It's the same as with most items:

Play a lot and have drop luck, buy it at trade or get one as a Kirac mission.

Means do Kirac missions - u get new maps to buy if u have started(!) one
(vendor reset).

But I am not shure if Kirac sells unique maps.
I think yes, but very rarely.
The same with map divination cards.