(Okay, we'll try to stop saying Benjamin.) For the results, Kayak looked at both domestic and international round-trip flights in economy class; evaluating search dates between July 1, 2016 and June 30, 2017 for travel dates in that same period. Of course, What are the cheapest days to fly? is a complicated question.
A Russian Soyuz capsule usually takes at least two days to rendezvous with the ISS, because of the carefully timed dance of manoeuvres that must take place for a spaceship to safely meet the orbiting laboratory. Using a new launch process, three astronauts have now made the trip in just under 6 hours.
All in all, your trip to Mars would take about 21 months: 9 months to get there, 3 months there, and 9 months to get back. With our current rocket technology, there is no way around this. The long duration of trip has several implications.