Although Coca-Cola collectibles are all around, trying to find other items by the company is difficult. There are very few sources for Sprite, Fanta, diet Coke or other non-Coke specific collectibles.
Even though it's not exactly what you are looking for, I found this can of Coke Classic, magically suspended in air, being poured into a glass. The Frozen Moments items are apparently made in Australia by Aspen Enterprises. I couldn't find anything specifically on the company or the Frozen Moments collectibles.
If you're interested in diet Coke collectibles, there is a great diet Coke resource page at www.jonsullivan.com/topic/topic-12-97.php3. This is the Official Home Page of Jon Sullivan. There are other things that might be of interest, too.
Of course, there's also the Coca-Cola Company's diet Coke page at www.dietcoke.com.