Here's some actual ceramic ones:  
http://silversurfervap.c...ceramic-flavor-disc.html I don't know about using them as a "Replacement" (as in for putting into a GVG), because I think they're a different size. But to use in a homemade contraption like a machine they should be great. 
No direction but to follow what you know, 
No direction but a faith in her decision, 
No direction but to never fight her flow, 
No direction but to trust the final destination.