Also: Even more expensive (much higher tech) is self vulcanizing sealing tape.

This is a very thin EXTREMELY flexible and stretchable SILICONE RUBBER tape (visualize a LiveStrong rubber bracelet flattened into a thin ribbon and wound onto a roll) that is not really tacky at all (you'll know it's the right stuff if it has a transparent plastic backing that you must peel off prior to installation.
I have personally only seen it in an orange color. There may be more color choices now.

This tape is also in the same section of the store as the electrical tape and friction tape.