I am fed up of being out bid at the last few seconds
Tightwad! That is because you don't think it is worth what the winning bidder is prepared to pay. If you 'snipe' too low, you will still be outbid. Just remember, to win an auction you have to bid more than everyone else thinks it is worth!
Another vote for Auctionsniper ... you get the first three snipes free and then pay a percentage, not a high percentage but it can get significant for high value items. I've used it for a couple of years now and it's never failed to place the bid as instructed.
It's got a couple of good features if you're after a regularly advertised item at the lowest price - you put the items into a bid group, set your bid amount and indicate the total number you want to buy. It stops bidding once it's won the amount indicated.
Recommended for the forgetful ... but not as exciting as placing the bid manually