Would love thoughts when I must have something

[oldjudge]

From your description it sounds like your item is in a live auction. If you can make yourself available at the approximate time your lot will come up for bidding perhaps you can arrange phone bidding with the auction house. I have very successfully done this in the past with several auction houses. If phone bidding is not an option I would try to arrange a representative to attend the auction on your behalf.
I would not leave an up to bid, but not because I'd be afraid the auction house would run me up. After all, what's your downside--maybe a thousand or so? Is that the end of the world for an item you have to have? No, I wouldn't leave an up to bid because if you can't live without this item perhaps someone else can't either and your up to, high as you think it may be, may still be insufficient. I still kick myself for an item I lost in the Halper Auction when I left an up to bid at 3x what I thought the lot would go for.

[boysblue]

I would definitely not place a high max bid. I did that recently on multiple items at a local auction and got run up to my max on every single item! Very annoying (though my bids were nowhere near the amount you are proposing). I like the idea of having a trusted family member/friend do the bidding for you. I suspect it will save you alot of money. Good luck with the auction