If what I heard on Dead Flip was true, I'd imagine all those who payed a deposit will get the discounted rate. I think BJM only went into full production in the last week or two, so I'd imagine none have been delivered to customers yet.
Stern's web page still shows the original price of $US6,500. Its worth prospective buyers keeping an eye on it over the next week:
http://www.sternpinball.com/games/whoa-nellie/whoa
