I think the most interesting aspect of the Mars Direct-style plans is that they can potentially be one-way. The largest expense with a trip to Mars in terms of

I think the most interesting aspect of the Mars Direct-style plans is that they can potentially be one-way. The largest expense with a trip to Mars in terms of technology and resources is getting back out of the Martian gravity well and back to Earth. If you go far enough into the Mars Direct-style approach, there's no particular reason why you need to be in any hurry to come back and you can think about sending crews in the dozens rather than single digits. I'm not sure I can see NASA doing a one-way mission, but I'll be first in line if SpaceX or whoever tries it.