You can build a product for less than $50k/month, particularly if you and your co-founders are deeply technical and if you have at least one founder who has great product and design skills.
Fred Wilson has been a venture capitalist since 1987. He currently is a managing partner at Union Square Ventures and also founded Flatiron Partners. Fred has a Bachelors degree in Mechanical Engineering from MIT and an MBA from The Wharton School of Business at the University of Pennsylvania. Fred is married with three kids and lives in New York City.