The first thing I'll say is don't despair. We bought our house for under the asking price two years ago. It was in VERY bad repair and the dreadful presentation also put prospective buyers off, which was good news for us. Our first bid was 10k under the asking price, then following a rejection of that offer we went 5k under. The EA took absolutely ages to come back to us each time, I'm talking weeks of waiting by the phone, but that's simply because no one else was interested. (There's a salutory tale here for sellers about presentation - the house was actually in reasonable structural condition but manky dirty - full ashtrays and disgarded wine bottles will put off the faint hearted!! but that's another post!)
Anyway to cut a very long story short we finally got the house for 2.5k under the asking price - we were bidding against ourselves in the end and refused to go the full whack when there was no competition. It was a tough battle and at times we came very close to giving into the EAs demands and handing over the full amount but they blinked first in the end.
There are some people, possibly even on this board who will say we should have stuck at 5k under, but we were absolutely 100% sure that it was teh right house and location for us so we were keeping that knowledge in the mix as well. Best of luck with it anyway.