CJ_Boxster, stick with OEM. Here is a link:
http://e-partssales.com/Merchant2/merchant.mvc?Screen=PROD&Store_Code=P&Product_Code=986plu&Category_Code=986maint
Do a search too, there is a lot of good info about Spark Plugs, other pricing that may be better than my link, and DYI's.
There might be other work you'll want to do during the SP change like the tubes and O rings.