They've made it ridiculously easy. You do it all on the website: Designate the type of chocolate (milk, dark, white, or milk and white combined) then pick your toppings. You pay for the chocolate base (from $5.50), then per topping, from 20 cents for a sprinkling of fleur de sel to $2.10 for gold flakes. Choose from fruits, spices, nuts, confections (like rice crispies or toffee), decor (a marzipan rose, or writing, like "happy birthday"), and grains (no, not farro; grains means things like candied lilac or the requisite bacon bits).
All in all, there are countless combinations. You could make a baroque bar: dark chocolate with candied rose petals, gold flakes, silver pearls, pistachios, fleur de sel, and goji berries. As you can imagine, some of these will get pricey. But they also have more sane recommendations in case the choices just overwhelm.