I didn't have too much trouble finding it. Here is what UESP wiki says:
Cyrodilic Brandy can be stolen from many nobles' houses; it can also be bought at the Main Ingredient or the Gilded Carafe in the Imperial City. Also, Bogrum Gro-Galash in the Lonely Suitor Lodge in Bravil has a chance of having it in stock. Three samples can be found inside the Odiil Farm just outside of Chorrol, and one sample is found at Cloud Ruler Temple in Jauffre's room, next to Martin's room.
Reference: http://www.uesp.net/wiki/Oblivion:Sanguine
Good luck! :foodndrink: