Just be wary about buying second hand OE ARBs. The OE bars have a design fault in that the rubber bushes are sort of coated onto the bar, so when they start to perish it causes corrosion of the bar which means an MOT fail I'm afraid.
I bought a second hand R32 one and it only lasted a couple of years before it caused an MOT fail so I ended up with a new one anyway....
Not an issue if you're only keeping the car a short while, but a PITA if you're keeping it to have to fork out twice.