Keep the OEM sprockets (if they are in good condition) and put a better quality chain than oem d.i.d. z10...
At 28K km i' d change only the shity chain for a AFAM XSR 7" 525 which cost me 90 euros.
The oem chain kit costs here 140 euros (chain & sprockets)... but i didn't like to put the "easy rusted' oem chain again.
I'd always change the front sprocket at least, as that's the one that gets hooky soonest and knocks out the chain.
JT are reliable quality and not expensive - I think M&P/Busters do them, among many others. You'll find that an aftermarket sprocket, without the rubber insert, will make whirring noise at low speed, but it's nothing to worry about.
AFAM and Sun-Star now produced front sprockets with rubber ring on..
In my case the oem sprockets are like new, they don't seem to have some wear at 28K km.