Check out this thread. A few of us, myself included, are building out cellars now.
You can build a cellar under $10k, easily. If you have a decent space (even just a 5x8) you can easily fit 1,000 bottles.
Some pros to a cellar are less refrigerator units running, aesthetics, better organization / access, once you get up to 800+ bottles they're most cost-effective.
Some pros to the EC are some redundancy (if one unit fails, you still have the other units running and keeping wine cool), if you move, they move.
I considered doing a wall of matching EuroCave instead of my walk-in. However, I have close to 1,000 bottles right now, so I would need 6 units for this to start making sense. At that point, I'm up to $12K and still don't have the capacity or aesthetic appeal, and it's probably much more expensive to run those 6 compressors than the 1 larger one.