I think you're thinking of the 2721 "grain of wheat" bulb. My local Advance (formerly Discount) store had some from Sylvania. I bought them in packages of two - a little less than $4 per package, if I recall correctly.

Edited to add: Sylvania and Phillips both use 2721 as the reference number, but it has other reference numbers from other manufacturers. I've also seen it referred to as a "W1.2W, 12 Volt".