I found them!

After years of unsuccessfully searching for those old, cheap, used-to-be-sold-in-grocery-stores Sheaffer pens, I finally found some on eBay. Still haven't managed to locate a transparent purple one, but clear, transparent blue, green, red, & black aren't bad! (Lamy Vista included for size comparison)

I used these all through high school and into college, to write letters to my friends, to write stories, sometimes even to draw with. I knew nothing about fountain pen maintenance at that time, and just stuck in a new cartridge whenever the old one ran out. I'd also switch colours all the time, and some of my notebooks have the most interesting gradation of colours as things went from, say, emerald green to lavender, or turquoise to red. (Brown to turquoise was pretty unattractive...) Ahh, nostalgia...