I've been trying out kits for educational toys, like slime and the chemical volcano, but one kit I just can't bring myself to buy-and-try is the rock candy kit. Why? It's around $12 and doesn't even come with the sugar... just a stick, container, and flavored food coloring. I can come up with my own jar and popsicle stick to make my own rock candy
and I suspect you can too. If you want flavoring, there are couple of ways to go. You can add a few drops of flavoring to your saturated sugar solution. These are extracts or flavorings that you would buy in the spice section of a grocery store. You use these by adding food coloring and a couple of drops of flavoring to your crystal solution. Cherry, lemon, lime, orange, mint, and cinnamon all work well. Another option is to dissolve Kool-aid™ or other drink mix in the crystal growing solution to (intensely) flavor your rock candy.
If you have experience with the rock candy kit and think it's worth the money, let me know and I'll try it out, but I suspect you can save your pennies and get equally good or better results on your own.
Rock Candy Video | Troubleshoot Problems Growing Rock Candy