I use a Snipe website nearly all the time, and feel no guilt about it as it wins me the auction (which is the highest bidder sale after all!!).
It means I never spend more than I decide at the start, I can be at work, or anywhere else for that matter, when the time is up so I don't have to hover over the keyboard (possibly getting caught up in a bidding war).
I don't always win, and in that instance my bid wasn't high enough, or another user Sniped my best bid, but that's the name of the game, and I am philosophical about it. There's always a part around the corner you'll get that will be better than the one you lost!!
Bill.................;-)