The new(ish) quadcopters require almost no skill whatsoever. When compared to a r/c helicopter you could say zero skill. When compared to an r/c plane, you could say 1/100th of the skill.
Basically they will fly by themselves. You simply use the joysticks to move them from one place to another. You can even (with some models) give them GPS coordinates and they will go there by themselves.
So line of sight is not a requirement to keep the thing "under control", or even to get it where you want.
And you can get this for less than £100.