The only "legal" issue with reselling is with promotional advances, but no one really cares too much about that (from my experience). I've bought plenty of CDs on eBay with a punch in the barcode and a "This CD is property of the label, it must be returned if asked for, etc etc". Doesn't bother me at all. The only place you might run into problems if you're planning on selling things at a local music shop or something. Some are picky about barcodes not having punches, some aren't. Some don't like CDs from BMG/Columbia House for some reason, some don't care. There's no legal issue with selling CDs from BMG/Columbia House, they're yours, you own them. But some places just don't take them since they are either 1) incredibly cheap (12 CDs for 1 cent!) or 2) they switch the barcode with one of their own on the packaging.