On first principles, this is actually a pretty easy thing to compound. If you start with water, add any sort of gelling agent, and a soluble ionic compound (for example, table salt,) you will get an inexpensive, reasonably conductive, gel. I suppose if for some reason it has to be a single pure compound, you've made the problem much harder. Note: you can't really get a good answer, because you haven't been quantitative enough -- you didn't say how viscous, or how conductive. Do you mean viscous as a very sturdy gel and conductive as copper metal? That also makes the problem much more difficult.