In all of the previous Guitar Hero games I've played, you could always unlock songs from some in-game "store", but I cannot find such a store in this game. Does it exist?
There is an in-game store with some things, but there are no longer purchaseble songs. I believe this is so that they can market their DLC songs and hopefully boost their sales. All songs can be unlocked by just playing the tour mode and going through the gigs.