Michael's does carry it. At least the one in my area does. However, it is not in the place where it seems it should be. My hubby used to work there and he took me straight to the glue and modge podge section where it used to be. They moved it. Spent 20 minutes looking around for the stuff and finally found it. It is the same type that Gweede mentioned, mold builder. I use it for corpsing my pumpkins. If you go back, you might want to ask someone. Usually somewhere among the employees there is one person who has familiarity with the products.
Hey everyone for what its worth I have found something that I love and it works amazing! I went to my local Lowes and found liquid latex in the form of carpet seam sealer. It does have a slightly stronger ammonia smell but its completely managable for using indoors. It is a bit thicker, which i like. Its very easy to work with and dries a bit quicker. Im guessing the extra ammonia does this. This stuff is tough as nails and the price is not bad i picked up 2 bottles 8 oz each for $4.89 a bottle. I hope this helps.