the current bid is 3530.. and GIN was 6600.. Listia 'disables' the GIN on ANY item once it reaches 1/2 it's GIN amount.. so when we got to 3,300 bid.. Listia Disabled GIN.. I asked the same question on one I tried to GIN a while back...
http://www.listia.com/support/topic/get_it_now
The Get it Now option is available throughout the duration of the auction, until a bidder has decided to use it. However, once bidding on the auction has reached 50% of the Get It Now value, the Get it Now option will be removed and can no longer be used.