I am Software Developer for almost 10 years now, i will continue doing it i think for the rest of my life.
I've been almost 6 years now as CTO of a Software Factory developing Technological Products, and i have a lot experience in the subject that you are referring.
You need a studio that understand your product, and take the time to understand what the idea is about, ideally with severals people from the Technical side who can understand a Product Process and how it can be matched with your product. That has to be your main goal, and not the Developers.
A product is build as a solution to a necessity, and developers usually do not understand that.
Also your provider has to have compliance with the most advanced techniques in Product Development (Agile, Iterative Increments, Change risks), and be available to manage the Development Team in that way.
Developer teams is an underlying issue, that can be solved with money and that's it.
A Team of 3 Developers, with a Product Owner and Coaching (Scrum) could cost between $10.000 and $70.000 a month depending in which country you hired.
And do not get yourself fool by golden salesman, a Software MVP must be out in two or three months tops, and be ready for retrospective and adjustment in the course for getting to optimal response to the market and strategical changes.
