k660 is not at all popular. you won't find any takers for that in Sony Ericsson Communities.
Else have a look at w595 though its 13k ! But its worth the money. Instead of buying a phone for 9k ! go for better phone w595 ! its more stylish and has quite a few other features.
w595 is good at everything except for camera.
k810i is nice except for old music player. k660 sports the new music player.
k660 is a good phone but its not popular, that's all. though customization and hacking it should not be tough, as its A2 and also 240x320 !