If you were wondering how many NPB strikes ebay will let a buyer have... check out this thread  remembering that some have the opinion that most sellers follow through with strikes and do not leave negative positive buyer feedback then those ones are anonymous then 

the neg/pos leavers on this guys feedback is only the tip of the iceberg  

http://community.ebay.com.au/topic/Selling/Buyer-Serial-Offender/600156750