I suspect many of us prefer the label "snipers" because we would like to be considered outlaws, predators, bad boys, rebels, etc. (when in fact we are mostly a bunch of people who spend too much time buying stuff online). But here are my first entries in the unofficial contest to find a "kinder and gentler" name for AuctionSniper:
AuctionThingy
AuctionPuppy
AuctionKitty
AuctionNiceComfyPillow
AuctionSnipingIsOkayReallyItIs