Hey guys and gals i'm having a bit of trouble figuring something out with the ds version of lego harry potter years 5-7, i'm wondering how do you buy and unlock the various characters throughout the game? i'm in the general hub and the only thing i've really been able to find is a cauldron with the polyjuice potion for changing characters and that is about it. i click on one of the characters it says that i can buy but nothing happens. at any rate if someone has figured out how to buy the characters in the game i would greatly appreciate any info they can provide.