On television, three was company, but in business, it can be awfully crowded. Still, some companies have made triumphs out of a triumvirate. Consider the case of Louisville, Kentucky-based B’s Purses, a website where customers can design their own purse, luggage or baby gift and even host a purse party or become a B’s sales rep. The 4-year-old company brought in sales of $2 million las…