In my recent trip to the Levenger retail store near me, I had a chance to browse through the odds and ends, and discovered separate covers.

• Junior size transluscent covers (frosty) ADS4285 - 4 covers (2 pairs) for $10 - $2.50 each
• Junior size transluscent covers in 5 colors ADS3815 - 10 covers (5 pairs) for $22 - $2.20 each
• Letter size transluscent covers (frosty) ADS4285 - 4 covers (2 pairs) for $12 - $3.00 each
• Junior size transluscent covers in 5 colors ADS3995 - 10 covers (5 pairs) for $26 - $2.60 each

They kinda hide them in the web catalog. I expect they want you to buy pre-built notebooks.