When I re-buy something, its usually a CD or record that I had when I was younger, but lost and/or destroyed (Nirvana's catalog, the Beatles Anthology series) or something that I was given on CDR and want to actually have for my collection (Radiohead's 'Kid A', the Yeah Yeah Yeahs' album, Avril Lavigne's 'Let Go' being a couple examples). Or, in rare cases, its something I have on vinyl, but not CD (PF's 'Animals' I didn't buy until just recently, and I've had the LP for a few years now).