What I have is a liquid purchased from a bakery supply store I bought after a cake decorator gave me her frosting recipe which included that as an ingredient. My bottle is a pint, so it's lasted a while, and I can't recall the price. They may have it in a regular supermarket with the other extracts and flavorings.
As for where, it's hard to say. I've been collecting recipes since I was a teenager, and don't have a record of each recipe's source. Sometimes, I end up looking at a few similar recipes and adjusting amounts here and there.
Does it save me money? I would compare a double batch of this syrup recipe to a bottle at the supermarket.
Cost calculations for doubled recipe:
.17 per cup white sugar from Aldi=3 3/4 cup=.64
.20 per cup brown sugar from Aldi=1/2 cup=.10
water=.00
The extracts/flavorings I don't have prices for, but considering there are 48 teaspoons in a cup, an average guesstimate of .10 each teaspoon could be close enough for this purpose.=.25
Total= around .99
So for me, there is some savings. It's also a nice alternative to be able to make instead of running to the store after realizing there isn't any on the shelf. So in that instance, it would be gas savings, too. And, although it isn't exactly health food, it doesn't have HFCS.