Yeah, there's supposed to be three discs. It beats me why Amazon lists it as a two-disc set, but I wouldn't worry about it. Amazon doesn't always give accurate info on their import CDs, but if it does bother you, you can send them an email and I'm sure they'd be more than happy to check. Amazon's one of the biggest online shopping sites there is, so they're
very dependable.
On the flip side, you can try the
CDJapan listing, which has it for quite a bit cheaper (4500 yen, which at the current exchange rate is about the equivalent of $38.82). Don't be fooled by the review by Sean Robbins at the bottom though - the CD set does NOT contain every BGM piece from DBZ (it's actually around a little more than half).
Oh, and they accept U.S. currency, if you're wondering. They automatically convert it and charge a small fee to your account, but all in all, this is still a cheaper method than Amazon.
BGM forever! If only more people paid attention to it... well, I intend to change that.