PSP Go Rock Band Unplugged?

I have been playing rock band unplugged on psp go for a little while now and I have yet to figure out how the hell to get more than the 5 songs that are already on there, I don't get it. Do you have to actually use real money to buy new songs? I mean I have buddy holly by weezer, abc by the jackson 5, the ace of spades, and blink 182, and foo fighters. I played several gigs and I still see no new songs. Anyone have some advice for this idiot?