Every terrain model tool can do something like . Terragen, world machine and many more.
Everybody spending a little bit of time in there can do something like the landscapes in the original posts with a few mouse clicks.
There is nothing in these scenes that can not be done by the majority of users here, and that makes them worth that amount of money.
Asking for $50, which is $10 for each of the landscapes is simply fishing for fools.
UE 4 is still very young and provides at stage the ground to make money with the simpliest implementations.
In a few years, when more people are familiar and know how easy stuff is, the post would probably be reported.