Hello!
It is rather difficult to find liquid FIMO in a physical store. Michaels
might have it, but I have had more luck at JoAnn's. A big problem you are going to run into with finding it, is that AMACO lost the big deal of selling FIMO clay, Faber moved the sales to another company. In the shuffle of all of it, some of the items were dropped into the abyss of the 'unknown'. As far as I understand it, liquid FIMO was one such product. The best place to find it is probably online.
Polymerclayexpress sells it
Here.If you do a google for Liquid FIMO quite a few places come up, but of course that is also all online.
Now, Sculpey has a liquid transfer as well. It is alright for most things, though IMO it does not work well if you need to glue something already baked to something that has not been baked. It tends to act a bit too runny to be really considered a gel. X_x;