I've been on both sides of the table when it comes to outsourced software and professional services. I've hired and managed single resources from oDesk/Elance and managed larger teams of outsourced developers. I've also managed teams of outsourced professional services resources on behalf of clients.

100x growth in 18 months seems to be very aggressive. Also a team of 25+ people to produce $50k in revenue seems to be very large, in proportion to return. In my experience, ensuring customer success and satisfaction is key. My concern would be that it's difficult to keep sight of customer satisfaction when trying to grow so quickly over such a short period of time.

That said, have you defined your differentiator(s)? Do you have a well-qualified team of client-focused people to manage your client relationships? Have you tapped-into your existing network? Given your experience at Goldman Sachs, I'd guess you have a pretty strong network that would be happy to hear how you could help them.

My advice would be to make sure your customer knows they are really heard, from your initial response to their very initial inquiry/request, in the proposal process, all the way through to project delivery. It still amazes me how many Elance responses are either form letter and/or don't address at least one of the requirements defined in my request, i.e. include a link to previous work.

Because the work itself is pretty much a commodity, differentiate yourself through the customer relationship - quality, consistency and exceeding the clients expectations.