Venture capital firms. The younger professionals at the top firms are smart, know a lot about technology business models, and are very well connected relative to their age. Plus, most of them got into VC not to become investors, but because they have aspirations of starting a company.
These ones are going to be the types that will be able to provide value on the business development side since they have the industry connections. (Tough to call them hustlers since it's not very clear whether they are "scrappy.") If you're looking for someone who can deliver on the product side, VC firms aren't going to provide those kinds of individuals, especially the younger ones. For product folk, it's best to poach Product Managers from slightly larger companies who are dealing with the same domain. They may not be as competent on the fundraising side but they will have a good idea of product & marketing.