After looking all over, I finally found gold on clear tape (IR-18XG) 18 mm for the Casio EZ-Label Printer. They've stopped manufacturing it and I was lucky to find a shop (a watch shop, how unlikely) that still had some. I knew it existed because the label printer box mentioned it. The thing is, since it's so rare, now I don't feel like using it!
I find it disturbing that it's not mentioned anywhere online how much tape is contained in one of Casio's cartridges. I was thinking, if someone wanted gold on clear so much and they stopped making it, could he buy gold on something and something on clear, and splice the 2 together?