This is too late, but I was intrigued by this concept of a free marathon (or marathon relay which you can divide however you wish). The Green River Marathon is taking place this weekend, and the entry fee is an "economic-tsunami"-friendly $0. A $12 T-shirt is available for those who don't feel comfortable with the concept of "free."
The catch? Well, if you are not comfortable with stopwatch timing, then forget about this. Also, there are obviously no medals and sparse on-course support.
The good news is that this is a Boston qualifier!