Comment on TF: Wheeljack and His Turbo Pie by Zanne
I found mine at my local craft shop, but you can probably find them if you possible have a JoAnn fabrics shop, or a Michaels...or if your local college has a bookstore, you can always check there for art supplies. :3 Fimo clay would probably work just as well; one of my friends uses that, and it seems to behave similarly. 
Oh I am in luck, we have a Jo-Ann fabric store in the mall ^^ It opened up while I was living in CO, down there we had a hobby lobby that I loved going to and really miss it. If I have to go online it's no biggy since I need to order a .03 mechanical pencil along with some copic multiliners anyways. I was thinking about going the traditional route for a while.