Here's my thinking: There are enough people here that would contribute to such an endeavor (and if there wasn't, the mechanics of GoFundMe and similar websites just return the money).
The incentive would be able to, once and for all, determine the actual likelihood of running ~12:37 clean. If no athlete were to run near 12:40 with a $1MM incentive, we would have our answer... that three running under 12:40 in the past was not just an anomaly.
Sorry this isn't very well thought out - in any case, I think we could do it.