The success of a startup consists of two parts - finding product/market fit, and developing the product. Steven Blank claims that for a wide class of web/computer technology startups the former is the ultimate risk item and deserves the most focus of the management (that's you). Hardly any technology startup fails for not being able to develop their product, most fail for lack of market for what they do develop.

If you agree with Steven, you are looking for a co-founder.

If you disagree with Steven, inquire with your local accountant about jobless marketing people. There are plenty right now, and accountants have wide social networks.