Ace-

First off fit is the most important thing (and it's worth spending money on).

As far as whether to spend the full $3000 now, versus buy an entry level bike now and spend more in a year or two- you can argue it either way. If you fall in love with a $3000 bike and are convinced it's the bike for you- go for it. On the other hand it might make sense to ride something cheaper for a year first (which will allow you to figure out what you really do and don't want in a bike- and when you do get to buy your dream bike you'll really know what you want).

I have a Serotta Coeur d'Acier that's designed as a tri bike and am in the process of buying a Serotta Concours road bike. I'm therefore probably a little biased, but I think a custom bike has a lot to offer. (My current Trek road bike is a really nice bike, but the fit is just not quite right.) I suspect it might be hard to keep the price under $3000 though. The stock Serotta bikes would be a little less expensive (and if you have a decent Serotta fitter they'd be able to tell you if you can fit one of the sizes or if you'd do better with custom or something else).

Good luck!