I’m not a fan, but it’s worth highlighting this new box set of Maria Callas’s complete studio recordings, in a remastered edition. (Amazon.com, Amazon UK) This is an expensive set: $275 or £211, but it contains 69 CDs, plus a CD-Rom with texts. (It’s even cheaper from Amazon.fr, at 199, and, if you’re in Europe, shipping is cheap; it will come to about £160, for example.)
You can still buy an older 70-disc set of Callas’s complete studio recordings on EMI at a bargain price (Amazon.com, Amazon UK), but the new set has New, Better Remasterings. (This may be the case; I’ve not heard either.) Warner bought EMI, so they are releasing the new set on the Warner label.
If you are a fan, you’ll probably want this new set. If you’re on the fence, you might want to buy the older set, at least if you’re in the UK, where it’s only £52; it’s $136 in the US, making it less of a bargain.