I suppose it is very hard to determine if the extra 10% was "wasted", because in reality there is a very high chance that if you don't pay that extra 10% you're not going to secure the property, and someone else paid slightly less than you got it and is enjoying the fruit now and you've once again missed an opportunity because of the extra 10% mindset that hold you back.
Same in Auction, you can't really kick yourself because you start bidding higher than the starting price and bid over the reserve price, and while you're outbidding other people you are pretty much over paying every time you raise the bid.
instead of focus on the money amount should focus on the % of the end result I'd say.