I use auctionsniper.com to handle all my ebay bidding. Their fees are trivial and the benefits are pretty high. Basically you make your bid through them, but they hang on to it until 3 seconds (you can specify the timing) before the auction closes, when their system places the bid for you.

The benefits are:

1) Their automated sniping system works pretty well, after more than 2 years of using them I've only had their system screw up and not bid on time once. They are "near" ebay in terms of network hops so their sniping is pretty reliable.

2) By using them, it is easy to retract a bid if you change your mind. Since the bid doesn't get sent to ebay until the last second, cancelling it is just a matter of deleting it from auctionsniper.com - the seller and all other bidders never even know you cancelled out, and thus no bad feedback for retracting bids.

3) Best of all, the more people who use it, the more prices are kept low. It is a "set it and forget it" kind of thing. With regular bidding, ebay wants you to put your maximum bid price in and they will auto-bid for you. The effect is that the price will increase as soon as someone else bids, possibly outbidding you immediately -- leaving plenty of time for you to change your mind about the max price you are willing to pay and sucumb to the temptation to bid "just a few dollars more." The more people who do that, the more the price ends up inflating.

Instead, with auctionsniper, you set it and walk away. You can set your max bid really high, but the price that everybody sees won't get there until too late for anyone to change their mind about the max they are willing to pay and "bid just a few dollars more." It makes ebay more like a silent auction.

I've saved some serious dollars using auctionsniper and eliminated all stress related to bidding too -- sure its fun the first couple of times, but when you realize that "winning" an auction is really about who can be suckered into paying the most, it isn't fun any more.

I'm sure there are other services/products like auctionsniper out there, I'm just very satisified with their service. They have some sort of referral program, but I don't even use it since over all, the more people using sniping services, the more price inflation is held in check so I just spread the gospel without worrying about any direct compensation from them.