a standard spark plug should last 10-20K KM...those better/performance type should last 30-50KM....
Spark plug is wear and tear part...
Also life span of spark plug depend on your engine condition...if your engine makan engine oil / wrong tuning then your spark plug will wear out faster.
I know not all of you are on drive-by-wire, but has anybody experience with a throttle controller, eg the Blitz throttle controller http://www.blitzpowerusa.com/products/throcon/throcon.html?