Plenty of games come with the minimum necessary number of dice to keep the game... er... rolling. A lot of time can be wasted just looking for the one D8 that came in Battlestar Galactica. Sometimes it's just another D6 that can really help out. The dice above are from Super Dungeon Explore and, fortunately, CoolMiniorNot offers a pack full to reduce time searching for them. Fantasy Flight Games offers packs like this for Star Wars: X-wing and Descent as well. Dice sets usually run $10-15 for most custom dice sets and many can be found at sites like Cool Stuff Inc. or a nearby game store if you prefer local.