machan - if u r concerned about music - go for the SE W series... K series is optimized for cameras... I had a K550i... camera is awesome - but not in low light.... music is also really good but I've read in many forums and revies that W series does music better...
On the other party - Nokia have been producing lovely phones that are too simple yet smart - I've been switching from being a Nokia fan to a SE fan for quite a time n currently I'm for Nokia (having a 2630 - cheap yet slim enough for me to love it)...
Sorry.. dunno about the prices...
1 more advice - buy from a reputed place - you could find phones cheaper in odd places but make sure they are upto standards (SAR n stuff)
finally protecting your ba..s

are important than buying a phone for several bucks cheaper...