I like both names, and think it's worth doing a little
research to see what established sites are using
the "half price" selling point in their names. That
should provide more of an indicator as to possible
value for your names.
Also, do many people search on 'half price fares'?
If they do, then this will also help to determine
value.
I wouldn't be surprised to see both of these sell
for mid $x,xxx each, and quite possibly more.
Good luck,