I've worked for an agency in the past which is not much more than two guys with a very deep Rolodex (both clients and potential workers) and a hired office. No

I've worked for an agency in the past which is not much more than two guys with a very deep Rolodex (both clients and potential workers) and a hired office. No permanent employees, only self-employed contractors. They only pay the employees once they get paid by the end client (normally after 30 days) and all the work is based on Statements of Work with large corporates so no real chance of non-payment. This is in the financial sector in the UK. Obviously they have feast and famine as well, but they have had 20-30 consultants all working at once. I think the main issue with replicating what they have done is a) getting the necessary client contacts, and b) the fact that banks are moving to preferred supplier lists with major consultancies rather than smaller niche suppliers.