Oh yeah . . . I have done the same thing.  One 
time I really wanted this cel on YJ and at the 
last minute someone came in and outbid me.  This 
extended the auction end time, so I rebid and we 
went back and forth for over 30 minutes.  Each 
time my husband and I discussed if we should go 
higher, but we kept deciding we really wanted 
it.  It is a rare cel and we justified it because 
it's a really great shot and a very rare 
character - you never know when you'll see one 
again (could be tomorrow, could be never).  As I 
said, this went on and on and finally we had to 
go to work, so we put in our final, final bid and 
left.  When I checked later - we had won!

It's one of those cels that I look at and think:  
Wow!  We really paid alot, but it was worth it to 
us because we love it :)  The only negative thing 
is it was a reseller that bid against us and 
drove the price up :(  I have been outbid by this 
person before only to see it pop up on their 
website for 2-3 *times* the winning amount.  This 
was a big factor for bidding as high as we did -
we could buy it now or lament later when we saw 
it for sale for over $1000.

So you are *not* alone :)  And, I wouldn't worry 
about walking up the price.  It's when the bidder 
inchs up bids by very small increments (like $1)
that's annoying to me.  Many of us change our 
minds for various reasons and bid more than we 
originally intended.

~Luna-Art >^.^<