On the one hand, a discount flight in and two busrides up and staying in the cheapest hotel you could find within walking distance (somewhat over a mile) to the conference so you can stay up with wifi working all night on the days you're not crashing on a friend's floor is a masochistically penny-pinching way to travel. I basically booked things until I figured I'd reached the Pareto point of spending money vs being more effective.
On the other hand, when you find out that two of your friends are driving to DC from Boston because they can't afford airfare (though really, with gas prices and parking and the extra time it's going to take them, I don't think they actually come out ahead) and are planning on sleeping on floors (floors of summer student interns, which are probably not exactly luxury living) and driving in each day, you know that's what you could have done, and in fact what your first instinct was until the "wait, seriously, is it actually worth the $40 I'd save to spend 9 hours on a bus instead of working?" logic kicked in.
I have spent 9 hours on a bus to save $40 before (which values my time at under $4.44 an hour and makes my back extremely unhappy). I still hike 8 miles across a city when daytripping for fun to save $2 in train fare in order to buy a hot dog for lunch. I see the city and get tasty food; I lose no work-time, and it makes me happy. Tradeoff!
Funny how the tradeoff point starts shifting.