Do check out the following sites for price comparisons of various flutes, but also call when you have your mind made up as they will offer significantly lower pricing over the phone from certain brands.
http://www.fluteworld.com
http://www.wwandbw.com
http://www.flute4u.com
You are looking in the price range of professional flutes and at around the same cost of the Yamaha 600 series you are looking at do try out Miyazawa`s PA201 and Altus` 807 flutes.
The biggest issues with Yamaha flutes is that it`s mechanism and tone even on professional models is supposedly inferior to the lower end models of professional flute makers from comments from professional flutists on those other flute forums I mentioned. However there is brand worship about and I only bring it up so that you know of those other brands so that you can test them as well and not find out about them after the fact.
The Yamaha 600 certainly is the better flute "feature-wise" if comments on "professional" flute makers really are hogwash.
However if looking at features alone if Yamaha quality is hogwash as well you may want to check out the high-end flutes of intermediate makers as well. For example the YFL-600 does not have full keywork. Jupiter, Emerson, Pearl, and Deford do offer the C# trill key and various rollers that facilitate better playing.
http://www.miyazawa.com/articles/options3.htm
You really do want to try before you buy and get the best flute for yourself.
The Yamaha is the Gemeinhardt of the professional flute world. You may find that it is only regarded for it`s student models and many advise to steer clear of the lure of solid silver for it`s basic student model until one can afford a real professional flute brand...
Pearl is actually better regarded as a professional brand for instance.
So check out other flute groups and see what actual professionals have to say in the matter if you really are going to buy on opinions.
Best of Luck.