Kav
While I admit to knowing next to nothing about the vintage watch market (although my knowledge is growing daily thanks to the info I'm getting here) I do know a bit about the vintage guitar market, and I would think the watch market works in a similar way.

Watch prices, like most goods, are driven by supply and demand. Vintage Monacos are expensive because a) the supply is limited b) the demand is high.

What drives demand? Sure, Steve McQueen has something to do with it, but it's not like he just started wearing them. And the watch is distinctive looking, but fashion trends change pretty gradually as well.

If there's a blip in vintage Monaco prices, I imagine it can be traced back to a single event changing the demand curve.

If Britney Spears was wearing a Monaco when she got married, I'd expect a spike in prices and a period of volatility.

And when Heuer reissued the Monaco I imagine it drove up prices because it a) lent a certain "it's a classic" cachet to the model. b) exposed the model to folks who frequent jewelery stores, but not watch shows, but who decided to search after an original. (I know that the Carrera re-editions got me juiced in that way.)

One of the reasons for the volatility of Monza prices of late is probably the fact that some buyers and sellers don't realize that the re-edition is a completely different watch.

That said, the one factor that tends to regulate price is information. And I would argue that with the internet and e-bay, the flow of information has never been better or quicker.

If found a beat up old Monaco in the basement of my in-laws' house, I can a) do a Google search and find ten dealers that have one in stock, including prices, pics and detailed descriptions. b) check e-bay for recent sales c) ask newbie questions at a place like On the Dash and get smart answers. (The Monaco is purely hypothetical, BTW)

Sure the watch is worth what someone will pay for it, but in 15 minutes, I can educate myself enough to know that a $500 e-bay reserve is too low. And a potential buyer will can figure out that a $4,000 Buy It Now price is too high. And as for its real worth, just put it up to a 10-day auction with good pictures and accurate descriptions, and I think the end price will be a pretty good reflection of what the watch is worth.

All that said, I think that sharing information--including prices and relative values--is this forum's raison d'etre, but smart buyers and sellers will take everything that's said here with a grain or two of salt and do their own homework before plunking down their hard earned cash.

allen