780Ti still a good purchase ?

Hello,

I'm looking to upgrade my computer and I have two questions.
Is the 780Ti still a good purchase? The pricing hasn't changed that much since it was released 6 months ago. In The Netherlands it costs about €600,00. I've read some rumors on the 880 but I have no idea when it's suppose to release.

My second question is if a 500 watt power supply would be enough to run the 780Ti.
My current PC:

• Gigabyte Z68MA-D2H-B3
• Intel Core i5 3570k
• 8 GB HyperX
• 2x 128 GB Agility 3 SSD's
• GTX 660Ti
• Corsair CX500

Thanks in advance.

Edit: Looking at the 290x as well. It's €390,00 here and performs not that much worse than the 780Ti.