That is an interesting idea about waiting the 90 days to Post feedback so you don't get the retaliatory negative.

I have found 99% of the time that it is the bidders with less than +5 feedback that are the troublemakers. They have nothing to lose really then they come back under a different name and do it again.

eBay will allow you to exclude bidders with a negative rating but not a 0,1,2 etc. rating from bidding. I sent that in as a suggestion to eBay.