Id pay a few hundred and I'm generally one who ridicules autographs and autograph seekers.
The key is to have "something" signed not just some piece of paper or your hat. If its something of intrinsic value, *then* its signed, that = $.
For Example:
Nick and Leo sign your cocktail napkin: Worthless.
Nick and Leo sign your Nike backpack: A few bucks, nearly worthless.
Nick and Leo sign your 2008 USA singlet: a few hundred maybe.
Nick and Leo sign *Nicks* 2008 USA singlet: add 100%
Nick and Leo sign Nicks 2012 singlet that he wore while partying all night in London after the 142...add 250%
Nick and Leo sign Nicks singlet from Moscow after he wins gold while wearing it and Leo wins gold and they slay every hottie in Moscow during a 2 day bender in uniform: I'll bid $10,000 right now.