I'm about to attempt to change the spark plugs on my 2000 jetta vr6 (42,000 miles)and i was wondering how important is it to change the associated wires. ( i was told by a vw mechanic that the kit for this costs about $140, so if it's not totally necessary, i'd rather not) any input would be greatly appreciated.

I woulnd't worry about the wires at 42K, unless you damage them when removing. There is a special tool to aid in this.