Well, not really. A bunch of people will argue that yes p2p is hurting the bands blah blah blah, but the truth is if you compare the amount of money a band makes off of something like itunes versus how much they make on tour - the itunes profit doesn't even come close. Especially now in the age of music where no one buys cds and singles go for 99 cents - when you buy a song nearly all of what you spend is eaten up by the big record labels.
Generally I'll only spend the money if it's one of my absolute favorite bands - otherwise don't even worry about it.