When I bought my initial /24 on such a site, it was not a competitive auction. I was the only bidder, and I paid the opening bid price, which was set by the seller. It's true that it was a real price, in that I paid it, but the 'auction' aspect felt like a farce.

They keep details private. It's not something transparent like eBay or a public auction. I think it's just a scam to pressure buyers into offering more.