If you have a MK4 arm, please see this link.
If you have a MK3 arm, please see this link.
If you have a MK1 or MK2 arm, please see this link:
If you need to identify what arm you have, the following link may help – Tonearm Models & Serial Numbers
The above prices apply to all variations of arm (eg. 12″, special cable etc) as they are more niche and add little to used price.