You really don't need an application to do this. I use esnipe.com. Their high speed servers will place the sniping bid 6 seconds before the auction close. It is very reliable and low cost.

You don't need any additional software for this eBay function. You can simply place a proxy bid and the eBay computer will automatically bid up to your maximum specified amount for you. There is no need for any external software.

This developer is the worst I have come across in a long time. I purchased version 1.3 a month ago. Saw that version 2.0 was available and downloaded it. Of course it installed over my original version and needs a new serial that I am expected to purchase. Communication with the company is rude, shallow and not the kind of thing the Mac community usually deals with.
Of course all the linbks to Silent Sniper go to version 2.0 and the manufacturer just says download it from where you first dowmloaded it. By the way version 1.3 never worked for me
William Whiston

Try jBidwatcher, it worked great for me. Ebay had made many change recently, and jBidwatcher was not always working, but now is it... well, if ebay didn't make any change :P
Anyway when jBidwatcher is up to date with ebay, it work perfectly :)