It was only a matter of time before this would happen. The Pokémon Go craze has now reached sites like eBay, where many high-level players are selling their accounts for hundreds of dollars. That way their customers will get bragging rights and access to substantial collections of Pokémons, without having to go through the trouble of actually playing the game.
If you have money burning in your pocket and want to be a part of the trend, but don't really feel like doing all that walking, this is your shot.
Beware, however, that selling and buying accounts is considered to be cheating in the guidelines developer Niantic Labs has set for the game. They probably don't have the power to pursue people doing this legally, but it would presumably be possible for them to ban accounts found guilty of foul play.