"I Did It!" sounds like something my nephews would say, just not my thing. I know I'm in the minority, so since that's added to having to buy it before you actually run a race, I'll just pass completely. I picked up finisher shirts in the post-race area at the Marine Corps Marathon and Nike Women's Half (the only races I cared enough to stand in line again to have finisher gear) after the race. There is certainly room for it at WDW and even DL, even if only back at WWOS or one of the DL hotels. The Marathon Monday idea sounds good, too.