My view is a bit different than some others here.
If I can get what I want at the price I'm willing to pay, I'll go for it no matter who is bidding. I expect others to do the same against me. No hard feelings on my part if I lose and, hopefully, none on the other if I win.
It's like playing poker. Some players have "unspoken agreements" not to raise each other if they are in the pot. Not me. I may be your best friend in the world, but if we sit down at the poker table I'm going for your throat. I play by the rules, am cordial at the table, but I'll take everything you bring to the table--if I can--even if I know you are on your last dollar, the rent is due and there is no milk for junior. I may lend--or give--it back to you after the game, but when we play, then we are going to play!
On eBay, if I want something I'll try to win, within the rules. But I'll use every advantage the rules allow. That means I snipe with a price I'm comfortable with. Usually I win, sometimes I lose. Too many people try to increase bids by a buck or two hoping for a bargain. So they are easily out-sniped when someone comes in in the last few seconds and bids what he is really willing to pay. I know some don't like sniping. but it's part of the game. As long as it is, I'm going to use it.
Do I sound cold-hearted? Hope not. I want to emphasize that I expect others on eBay to treat me the same way and I have no hard feelings if I lose an auction. I think you can still be friends even in a competition.
Cheers,
Russ