we're preparing a completely free version that's only limited in the size of layouts that can be planned.
RailModeller Express will be available in a few weeks!
In the meantime you might want to join our beta mailing list;
all beta releases are fully featured and don't currently require that the app was previously bought on the Mac App Store.
Hope this helps,
our free Express Edition is now available:
RailModeller Express on the Mac App Store
For a description of RailModeller Express and how it compares to the Pro-Edition please have a look at our product page.