As a non-technical single founder for a web startup, is it better to hire a design firm to build the prototype, or find a technical co-founder?
Find a co-founder. The problem with using an outside agency to build your initial prototype is that you won’t really start learning about your product until after you have launched it. You need to have the talent available in-house to then make changes and improvements based on the feedback you get from real users.
Don’t put yourself in a position where you’ve spent all of your money on external development before you learn that you haven’t built the right thing. Launching the prototype is just the start of your development process.