I'm not sure I understand the question? Do you mean like flipping sites?
I currently have 3 websites I work on, and I will probably add one more to sell. Selling or flipping is incredibly difficult, however, because you have to have a lot of content, a community forum, and usually a product the person your selling too sells too for the Affiliates part.
I have a lot of web development under my belt, so I'd definitely make a site for a paying customer.
It's definitely a good niche as well.
XoFrame