depends on what you need it for.
The world and its desires pass away, but the man who does the will of God lives forever.
-1 John 2:17
Yes, the wood choice and craftmanship that goes into a guitar like the taylor 9 series makes it worth it. That being said a $2000 guitar like a taylor 4 or 5 series will sound great but will never be a "perfect" museum piece. Which makes it more desirable for playing gigs.The difference between a midrange 2grand guitar and an entry level laminate or ovation does make a much larger difference than between a 2000 grand and 4 grand gap range.
1990 Gibson LP Studio
2007 American Deluxe Stratocaster
2006 Taylor 510-ce
Fender Geddy Lee Jazz Bass
Mesa/Boogie DC-3
If you're willing to pay 4K, go custom. that's all I can say. I think a custom 4K guitar is worth much more than a 20K production guitar.
will someone carry me across ten thousand miles under the silence
Solid seasoned wood of the right type and well executed joints and bracing are things you have to have for excellent acoustic tone. The saddle & nut type and finish, bridge, even the glue used makes a difference. I play the banjo, and high end banjos cost a lot. There was a big thread a while back on another site talking about how much it costs to make a good banjo, and the parts alone came up to something like $800 before you even started factoring in time/labor/inlay work. There are some features and things you have to have for the best tone.

At some point (I don't know exactly what that price level is) you've paid for the seasoned wood, the parts, and all the labor and fine craftsmanship to make the guitar. Beyond that you're paying for more inlay and ornamentation and in some cases a name. A high quality guitar that's been played a bunch will usually sound better than a new high quality guitar because the wood is more broken in.

That being said, my cousin has a $4,500 Taylor dreadnought, and it is absolutely the best acoustic guitar I have ever heard or had the good fortune to play. My Dad and brother have several expensive Martins and they don't sound as good as this Taylor.
Wow, I realised that I totally misinterpreted this thread. I thought you were asking for good 4K guitars, not just 4K guitars in general. My bad. :\
All I can say, is this:
When you've played one you won't have to ask the question!
will someone carry me across ten thousand miles under the silence
It's worth it if you enjoy the instrument and have extra cash lying around. Otherwise, no.
- Art & Lutherie Cedar CW (SOLD! )
- Martin D-16RGT w/ LR Baggs M1 Active Soundhole Pickup
- Seagull 25th Anniversary Flame Maple w/ LR Baggs Micro EQ

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Yeah, I guess I'll have tostay satisfied with my 200$ one... ah...
The times they are a changin'.....