There is a shop called The Succulent Source that really caters to people looking to use succulents as wedding favors as well as in bouquets, boutonnieres, favors and centerpieces.
If you're looking to buy cuttings to create boutonnieres, bouquets or cake toppers, they have a great selection for you!
Another fantastic and really unique option for succulent centerpieces are wine bottle planters. Looking Sharp Cactus creates some amazing succulent arrangements in wine bottles. You can either buy the wine bottles or get them and fill them with your own succulents.