I personally put a huge value on a piece's history....but that is not to say that it should necessarily affect the value. There have been occasions when, if I felt the piece was priced a little high, I'd go ahead and bite the bullet if it had a unique story....but that's just me being an undisciplined, passionate sucker for great advertising.
Although it's super-kool to see the Pegasus in it's original location, I doubt that the specific provenance on this sign affected the end bid. Embossed horses are not exactly "rare" but sure enough ones as clean as this example aren't frequently available. In every category of collecting, value is directly proportional to condition.
I agree with Dave in regards to average sales price and, although expensive, given the high quality, imagine it's not that far out of bounds. If anything is going to increase in price it's going to be the upper end pieces as it pertains to condition and/or scarcity.
Another thing to remember is that every transaction is unique.....even when comparing apples to apples. Can't say mine is worth X because one like it sold on e-bay for X. The people involved, the mood of the person that day, the venue, and the particular piece (no 2 are exactly the same)all figure into the final price.
Will this buyer have preserved his capital? Perhaps. It's certainly something to consider when investing such a large amount but really, if you can afford it and absolutely love it, who cares? I never buy with the intent to sell. I may be forced to one day and even if I lose money, the joy provided during my temporary stewardship is immeasurable.