Well, yes, you cannot outbid yourself. But there was a glitch on Ebay a few years ago which I did outbid myself by increasing my max bid (and eventually nobody out bided me), it was only 1 or 2 pounds though. Over the years, I have had only a few unhappy incidents early on, that was the time when buyer protection was not in place. I think I am getting slightly smarter these days. The other thing is that, I am using ebay more as more as a 'buy it now' shop than an auctioning site these days.
Yep, 'Buy it now' or nothing for me these days; I can't take the disappointment of waking up in the morning to see I was outbid.