http://cgi.ebay.co.uk/HKS-S40i-Iridium-Spark-Plugs-for-Nissan-Skyline-300ZX_W0QQitemZ330211538764QQihZ014QQcategoryZ72205QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
some here on ebay. 80 quid . i 'd rip smithys hand off at 55 nicker if i were you . :)
i use autoglym leather cleaner and then apply autoglym leather cream after ,with really excellent results .
you will be surprised how dirty they get.both good quality products.