Contact your nearest dairy or milk distributor. L
. Heehee. That's what I thought when I read the title ... until I Googled it. "Liquid emulsion" is commonly used to refer to photographic emulsion (the first page at Google is all photo emulsions). Also on that first page were suppliers of said emulsions, so "decent price" must mean something close to "free."
It's probably paint, but if someone is going to be vague... L
. I agree that it was very vague, especially for ppl such as I who are not Crafts-capable. I imagine it was doubly so for a Chemist. :) That was just a piece of trivia I thought you might enjoy. There's still a decent chance that the OP was talking about something totally different than photo emulsion.
What end product are you expecting to get? There are about 50 different kinds of emulsions available and it you start out with one designed for one use it can't be used for any other use.