average repair for valve job or piston/rings 2001 kawasaki 250cc ninja?

[grlnextdr]

i know it's either one of the problems please hurry i'm holding my breath
first of all, to the harely dude and towing it to the junk yard, i don't need sarcastic comments save my space for real guys and girls with real answers. you must be a pleasure to be around! now.....i had the bike checked out and there was oil on my spark plugs this is how i know it's either a valve or piston/ring issue thanks to all in advance

 

[mushki]

Either way not cheap. Valves should be cheaper but still will be over $500.

 

[krazeekaci]

parts may not be expensive but laber wise it will be