Since this is an auction based on blockchain technology I am selling something that exists on a blockchain that is unique. Today, I am offering the namecoin DNS address steemchain.bit at a starting price of 5 SBD.
Photo Source: namecha.in
The .bit domain is served via the cryptocurrency Namecoin infrastructure, which acts as an alternative, decentralized domain name system.
Use of the .bit domain requires a copy of the Namecoin blockchain, a supporting public DNS server, or a web browser plug-in. And unlike commonly used domains, registration of this type of domain is not associated with an individual's name or address, but with a unique encrypted hash of each user.
Source: Wikipedia
Anybody who chooses to buy steemchain.bit can do such things as mirroring their steemit posts on ZeroNet.
Photo Source: namecoin.org
Auction Details
I am using 
Name of item: steemchain.bit
Quantity: 1
Type: Blockchain asset/namecoin DNS address
Starting bid: 5 SBD
Buy Now price: 50 SBD
How To Place Your Bid
Reply directly to this post with "bid x". Example bid reply: bid 5.0
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Bids will be accepted until the end of this auction.
I will transfer steemchain.bit to the highest bidder after payment has been received and the highest bidder provides a namecoin address to transfer steemchain.bit to them. The highest bidder must make sure it is a namecoin address they control because resolving the .bit DNS address requires control over the address (e.g. DO NOT ask me to send it to an exchange address!). If somebody bids the 'Buy Now' price of 50.0 SBD I will end the auction after seeing the bid has been posted and the auction for this item will be over. Obviously the first one to bid 50.0 SBD gets it even if higher bids are placed. After the payment is received steemchain.bit will be transferred to the namecoin address the highest bidder provides.
Well, that should do it. Let's start the auction.