Scott, there is no limit to how large you need to be to be a B Corp, so long as you are at least 6 months in business. The certification fee is also on a sliding scale, so it will be very small for a company with modest revenue. B Corps have a strong tradition of buying from one another, that along with the myriad discounts available to certified companies adds up to a lot of growth potential. And you get to improve the sustainability of your enterprise through the help of third party standards and a community of like minded companies. Go for it.