I would not end the auction early (the price always goes up at the end most times), and I wouldn't bother to make your reply public. My experience is that most of the time when I get asked this question to end an auction early, the buyer just wants to get a good deal before the price gets up too high.

If you think $50 is a good price, by all means have the person bid and then end the auction with a $50 bid...But if a person is willing to offer you $50 on the item with 6 days to go, then it must be at least worth that much....

I always let the market dictate the price and it seems to work okay....

Randy