I'd go $350Unfortunately the whole "previously owned by the athlete" thing doesn't really add any value, unless you find a buyer who obsesses over that particular athlete.
The Warrant isn't a particularly popular watch; on average they sell for around $250. Being a less common version, you might get up to $500 for it, unless you can find a sucker with more money than brains.
If I'm off-base I'm sure someone will chime in.