Suppose a few friends got together and wanted to create a usatf sanctioned and certified course

Probably insurance and all kinds of stuff.

If you're serious about this, I would ask these guys what they did:

http://www.premierraces.com/lastchance/lastchanceraceinfo.html

It's a marathon run in one-mile laps around a parking lot, for the main purpose of being a minimalist, last-chance Boston qualifier.

Course certification is relatively easy. Just get an approved course certifier and he can measure your course, make the drawings, and send them in the USATF. I believe a course certification is good for ten years. Prices vary but it is pretty reasonable overall.

Sanctioning is a whole different ballgame and not worth it if you aren't putting on a public event of some size.

Ummm....have you ever heard about a marathon on a track? It's the latest craze.

I've created and directed many races before - certification is not an issue, that's been explained already in the thread. The issue (if you are time-pressed) is that you will require road closure permits and policing (unless you are planning to do it entirely off-road, which I'm guessing not), and this takes time. You can't just walk into city hall and demand road closures for a month from today, at least in most cities I'm aware of. They have planning committees and so on, and generally it's a process of up to a year, depending on your luck as to when the next meeting is held.

The actual cost of the road closure permit is surprisingly low - but the policing is not, and they decide what the race route will need in terms of cruisers, supervisors, and officers - not you.