I don´t think Wolphs "blind bidding" in the last 5 minutes works, but I think he´s on the right track.
I´d leave everything as it is, just that I wouldn´t "extend" the timeout for an auction for more than 5 minutes in total at alll. So if a player sells on 9:30, he will sell no later than 9:35.
If someone else places a last second bet on him, on that last deadline, fine. No option to "react" anymore. So if you want that player, better make sure that ...
(1) you offer some "serious" money, maybe even "overpay", before the hard deadline appears.
(2) don´t take that "miniumum" raise for granted.
So for example, player X should sell on 9:30. You place a bet on him, and nothing happens, until a last second user decides to take a shot at him shortly before the deadline expires. He gets extended to 9:33, as it is now, and both teams enter a classic bidwar, just that after the deadline extended to 9:35, no more "extra time" is added. So after 9:33, everybody has to change his strategy, the forever-minimum raising stops, and people kinda have to play with open cards.
Zwei Dinge sind unendlich, die Dummheit und das All...