Guildmaster's special is normally sold in the guild bar but I've never been in the elf guilds to see if they even have a bar let alone what is sold. If its not on the menu there, it probably should be added.

Stunning drinks are pretty common in other places, I'm fairly sure I could lay my hands on a dozen freebie varieties around the Landing without needing to pay the guild barman 1000 silvers for the Special.