I had never heard or used it until I went to Midwest Haunters Convention this year. I don't think they sell it at spirit, sadly, but you never know, they might. I probably just missed it. I ordered it online and they are very nice people with great customer service. I got a gallon of the swamp juice.
You can go to their web site: Froggy's Fog and order directly from them. They have the best price on the fog, and depending on where you live (they're in Tennessee) you might be able to do better on shipping. (For me, it's an extra $10 to ship from Tennessee to Seattle, Washington)
They are also listed in Amazon.com. Here's the link:
I ordered a gallon of the freezin fog from amazon.com and should be getting it any day. I hope it will be enough, I've never gone through more than a couple of the small bottles before. I can't wait to try it out. I have one fogger that is the kind you put ice in so I'll use that one. It is just a little 400 watt The Fog machine brand, but I love it.