That's odd... the interviews I've had to travel for were all compensated. The companies actually bought me the tickets, set up the hotel reservation, and got me a rental car, so all I had to worry about were the meals.

Edit: Just talked to a friend of mine who does interviews for her company, and apparently there's been a paradigm shift of late. Since grads want jobs more than employers need them, there's been a power transfer between the two. Instead of the employers courting grads, it's the other way around now.