DJM 800 Knob's

Hello

I own a DJM 800 Mixer. In years of usage the Knobs on the mixer are destroyed. The rubbered part of the knob is destroyed, the feel when you touch them it's not ok. 

I saw on eBay various knob's but i prefer to get the original one. But hey, 15-20 € for one knob? I need 16-20 pieces of...The cost would be insane.

Where to find genuine one's for less money? :)

TNX