As others mentioned, placing a bid on eBay doesn't cost you anything. More importantly, these penny auctions lack is transparency. The argument is that they're

As others mentioned, placing a bid on eBay doesn't cost you anything. More importantly, these penny auctions lack is transparency. The argument is that they're not gambling because it's a game influenced by skill, but for that to be true you would need transparency into who many bids have been made, by which people, with what timing. This doesn't appear to be possible without running an aggregation script.