I am wondering, as you guys have mentioned above about FX being able to produce more shallow DOF and better bokeh and to shoot at high ISO , is it worth enough to spend more than $3,000 just to get those advantages, especially for those who just doing photography as hobby?
To answer your question, no. When you buy a DX camera such as the D7000 you get about the same complexity as the D600 at (currently) less than half the cost. Buy the D7000, use it, learn the difference in the way it affects you in your fields (i.e. macro, sports, portraits, landscapes cityscapes, nightime etc. then make the decision. If you buy an FX lens to go on that DX body, you can take it with you if you go to an FX body.
As said before, DX is a positive advantage in many fields of photography, not a disadvantage across the board. View the PAD thread to see what cameras people are using and you will see that the difference in quality of the images is more to do with talent and lens than body or sensor size.
Be logical - it is when you lose control of your mind that the cost of this hobby gets way out of hand ;-/