Dice are supposed to be one of those "evergreen" no-brainer products that every game store not only sells, but can't get enough of. It is true that everybody needs dice, and it it is true that some people have something close to an addiction to dice, but it does take some effort to have the right dice.
There are three dice companies worth noting. Chessex is the dice champion, the one to beat, the gold standard in dice. They sell those "bricks" of dice you've probably purchased, along with loose dice that I've recently started buying. They come out with new lines of dice twice a year, like a fashion show. There are actually customers who come in looking for these, so it's a big deal.
Koplow is a big company too, but you may have not heard of them. They tend to sell a lot of bulk dice products, specialty or educational products and the dice game that sells metric buttloads during the holidays, Left-Center-Right (LCR). I started an argument at my first game convention by getting the head of Koplow and the head of my main distributor to talk to each other about why I could never get any Koplow stock. They each blamed each other. I was learning.
Finally, at the boutique end of the spectrum we have Crystal Caste. Crystal Caste makes the dice you would buy if you hit the lottery. They've got sets of bone dice (real animal bone), iron, semi-precious stones, and various other high-end materials. They used to sell beautiful plastic dice called "dragon bones", but as far as I can tell, there is a limit to how much a gamer will pay for a dice set. Q-Workshop, which makes $20 sets of runic dice, is a good example of this. They make beautiful dice that no gamer will pay for.
We sell dice in the store in two ways, in "bricks" of dice, plastic cases of polyhedral dice or D6's of 12mm and 16mm, or loose in acrylic displays. For bricks of dice, Chessex is the brand of choice. Bricks of dice are easy to sell. They're tracked, they're pretty in sets, and they're as easy to sell as any other product. It's the loose dice that make me a little insane sometimes. When customers come up with handfuls of various dice, it's up to use to manually enter the price, remembering what ever style costs and identifying the little buggers. Identifying a "pearl" from a "marble" isn't always easy. Sometimes they actually ask questions about the loose dice (groan). "Do you have this style in a light green?" Loose dice are just there. We buy them in bulk. We get what we get. Just buy a brick for the love of god. That's what I want to say, but don't. When I tell you about the role-player dice customers, you'll begin to understand.
Because they're not part of the inventory, loose dice never appear on sales reports, other than a generic dice department. Therefore, they're off the radar, out-of-sight, out-of-mind. Anything off the radar that takes effort is something I generally have disdain for. Then I'll look at that other department report and realize I need to re-fill the displays. It actually is worth the effort.
The bricks of dice don't automatically sell. I used to believe this and I carried every style of Chessex dice. That's right, all of them. When I finally did the math, I realized that my dice sales were pretty slow compared to the rest of my inventory. I slashed and burned, putting on sale about a third of my dice stock, blowing out the ugly multi-colored speckled varieties and colors that generally don't sell. Some unsellable sets were opened to make displays of dice. Yellow, for example, is known as a color with limited appeal, as well as various shades of brown. Pinks sell well to certain people (not always women), but are worth keeping around. I manage dice pretty ruthlessly, dropping those that don't sell within about 6 months. After a year of this, I came up with steady sellers, and combined with new releases twice a year, the amount of dice is probably back to where it was when I had everything.
There are three groups of people who buy dice. The role-players buy sets of polyhedral dice and occasionally matching D6 sets. These are sets of 7 dice: D4, D6, D8, D10, D12, percentile, and D20. The "D" refers to die. They inevitably ask for sets of D8's or D12's or something similarly not available. They key there is to hunt down Chessex at the local conventions. It's the only place to find quantities of a particular die types. RPG gamers tend to be the serial dice buyers, collectors, or addicts. They tend to have dice "collections" and will buy a new set of dice for each new character, or just because they happen to be visiting a game store (god bless them).
The wargamers are far more utilitarian. Dice are something they would be happy to borrow or use a community set. A role-playing would shriek in horror if you asked to borrow their dice. "What! You'll roll all the luck out of them!" It's not uncommon for a role-player to replace dice because they stopped rolling well, or a particular key die failed them in a time of need. Or someone touched them. Meanwhile, the miniature gamer is looking at the bottom of the dice cube at the price, attempting to find the cheapest set with the highest appeal.
The third set of dice buyer are the bar crowd. These people aren't gamers, at least from the perspective of the gamer sub-culture. A better description would be bar fly, or maybe dice skank. I know that sounds harsh, but these are not standard general public folks. They're mostly women, but occasionally a man will come in and buy for the others, kind of a dice pimp. The women are notable because of the tattoos, tight clothes, lots of cleavage and mangling of the English language. I kid you not! These ladies are all about the bars, and their one and only game is liar's dice. They tend not to like our style of dice, preferring square cornered dice rather than the rounded corners of most gaming dice. What they do enjoy are the colors, and it's not unusual for them to spend an hour or more sorting various D6's on the counter, looking for just the right color combinations. They'll empty the bins completely before choosing the ten dice they like. They never spend more than ten bucks or so, and never buy bricks (but always ask if they can break brick sets).
Before you laugh at all these various gamer geeks, let me tell you, it's contagious. I spent years with a small collection of dice, just enough to play a role-playing game. It wasn't a collection as much as a sack on a shelf somewhere. I thought little of it. After owning the store, things changed. I had to have a different set of dice for each character, including a matching bag. At one point, my giant in-store collection wasn't enough. I trolled conventions looking for pre-release dice that weren't available elsewhere. I even paid full retail for these beautiful random number generators, when I could have bought a set in the store for half that. It rubs off on you.