This is a thought experiment. If you were starting an architectural firm today, how would you do it? At the time of the American Revolution, what did an architect's office look like? Probably not much different than in 1900, except the projects may have gotten bigger. In 1976, what would the differences have been? Well things have changed on the technological front. There are electric lighting, telephones, electric erasers, adding machines, light tables, automobiles for site visits, diazo and mimeograph printing for plans and specifications respectively. There is still that timeless part about needing a client with a project, however. Programming is more sophisticated. But designing and detailing a project isn't really any different.
What about today? In 2013 what would be different? What could be different? What should be different? Except for that timeless part - a client with a project - EVERYTHING!
You don't need: an office, a phone system, a plotter, a fax machine, a library, flat files, a conference room, a reception area, a server room, a network, a GBC punch and binder, past project files, etc.
What DO you need? You may already have some of this.
Computer - $1,000
iPad - later ($750)
Smart phone - $200
CAD - DesignSight - FREE
Basecamp subscription - $25/project for now
Invoicing System - PayPal account
Bookkeeping service - Wave - FREE
Insurance - later ($500) - once you have work
Website/Domain/Email - Weebly - $100
Google Apps with Drive - part of Weebly
Dropbox - FREE (for additional shared storage)
Wide format printer-copier-scanner - $300
Total to get started - less than $2,000 the first year, and about $200/month expenses.
You may not need employees for some time. You can farm out work that you need help with to other self-employed architects, who could be anywhere. India? You really can't overstate how much Internet-based services change the need to be in one place with your design team. Add Google Hangout to your repertoire with its ability to share your screen with up to 10 people and you may just be old-fashioned if you think an office is necessary.
So, work on getting that client. That is the only real barrier to having your own firm.