How to start a new ISP in a small city?

Does anyone have any insight on what it takes to start a new ISP (like Comcast, but at a smaller scale)?

Do you need a significant amount of money to even get going and lay your own infrastructure? Or are larger companies like Comcast required to sub-lease their lines to smaller companies (so they don't have a monopoly).

It's going to cost a ton no matter what. Infrastructure aside, the networking expertise you're going to have to pay for is significant. Plus the costs of marketing, sales, and installation equipment, crew, & training.

Some Tier-1 networks do sell access to their infrastructure. A couple are:

• AT&T
• Cogent

An option to build your own infrastructure could be to work with the city government, and see if you can get state & federal grants. Here are some news stories about small towns doing this; some of the cost details are illuminating:

• Small Alberta town gets massive 1,000 Mbps broadband boost
• Small town of Ellensburg approves plan to build publicly-owned fiber network
  
• German villagers build own broadband network
  
• Fast fibre: A community shows the way
  
• How One Man Built His City a Fiber Optic Network
  
• How Chattanooga beat Google Fiber by half a decade
  

Most of the local ISPs are actually hooked into Level3. You can think of them as the "ISP for ISPs".

Here's a relevant question that might be of some use:

Who provides the Internet service to Internet Service Providers (ISPs)?