I'm in an Ebay bidding war, how high should I go?

I've recently been on the hunt for an antique hanging store/kitchen scale.  I thought it would look good hanging over the kitchen sink.  

Here's what it looks like

I have not bid on a lot of items on Ebay (I've always gone for the "buy now" purchases)

I went about this the wrong way and started bidding when there were 5 days left to the auction. There is another bidder who wants it just as much or more than me.    We have taken the price from $10 up to the current bid of $36 (not my bid).   There are 2 days, 7 hours and 52 44 minutes left in the auction.  I finally decided to relax and let it be.   I will wait til Monday night at 6:30 pm and as I watch the count down I will zoom in at the last minute and scoop it up. That's if I remember and get home from work in time.

I have no clue what a good price is for one of these ... does anyone have any advice for me?

** Feb 28 Update:  Thank you for your advice on this, I just checked the current price and another bidder is now involved in this auction the price is up to $45 so I think I will walk away.  I have to consider the shipping price on top of the purchase and I don't think I am that in love with this scale. There will be more scales in my future now that I have put the desire out there.  I will add to my list for the local antique shops ... Hanging Scale, Ball Mason Jars - Blue, Chenille Bedspread in good shape, and much more ...

Jo