As I understand it, Sanctuary's economy is in turmoil, and drinks like the Free Drink cost more. However, in Lower, the person who sells adventuring supplies seems to sell it for 1gp, while the seekers sell it for 10-20gp.

I missed the Seeker HQ when I most recently adjusted prices.

"The Free Drink" should be pretty cheap stuff. It's the sort of drink you'd only want after having just escaped decades of enslavement by the monsters of the Underdark.

Fixed.