For those of you renting at the end of the month, I think it's just too early for your rates to drop.
My rental is sep 6-15 and it just dropped mid-week last week.
So be patient.
For those renting early in the month who can't get the rates down, I can only guess it has to do with your particular dates or number of days.
My rental is 9 days, but when I played with the dates and took just 1 day off, the rate went through the roof!
As of yesterday, mine went from $161 to $430.
Thank goodness I booked when it was down!!
My advice is to check constantly.
If I had been just a little later checking yesterday, I would have missed the final drop on mine before it shot back up.
I am still hoping for a lower rate before I leave, but if not, I can definitely live with what I have.
Good luck to everyone!