This topic is not related exactly to this question but I know what you mean.
Here you should be selling your old websites or businesses that you want to sell.

But I saw people who are creating website per day with unique domain name, design and webhosting and they sell it on ebay or in forums like this. Usualy those websites are having affiliate program promissing you earnings after some time. All you have to do is marketing around and bring traffic there.
For the designer is profit in the sale itself can be 1 dollar but mostly in the webhosting fees or referral commission.