Turnkey websites usually refer to somewhat established sites, that already get a decent amount of traffic/customers, and can simply be flipped to a new owner who can instantly start making money from them.
I would think that it would be nearly impossible to create a brand new site within only a day or so that instantly makes any amount of money. Otherwise, you should be creating such sites every single day of the year :)
What Dani said. However if you are asking whether there is a market for flipping websites and doing it yourself.....The answer is yes, heck the lazy man's approach is just domain flipping itself so yes it is possible but you need to do alot of research on how to increase the value of a domain (there are ALOT of factors). With a good inbound link network and a solid understanding of SEO you should be able to pull it off in a relatively decent amount of time. I'm sure google will be able to help you get started with a few good tutorials and notes on others that have spent the last decade+ doing it.