You can buy a vinegar jar, but I found it cheaper to make one.
Step 1: Ceramic Pot and Spout
I picked up the ceramic jar from a Chinese market and the spigot from amazon, each for a few dollars.
Step 2: Drill
Use a tile bit to drill a hole in the side of the pot.
Step 3: Spigot
Insert the spigot through the hole and attach the rubber seals before tightening the bolt on the inside.
Step 4: Finished
Brew some vinegar.