I buy CDs at ArkivMusic for a number of reasons: great sales, good prices, and the availability of out-of-print sets. They've negotiated deals with some major labels to press-on-demand a range of otherwise unavailable sets. That's how I got my copy of Satyagraha, for example.
I get email from ArkivMusic once or twice a week, and usually have to bang my head against the wall a few times before clicking Delete, since I already have dozens of sets I've never heard. Currently tempting me is a boxed set of orchestral works by Mexican composers. Back, back, I say!
Not tempting me, because I already own the set, is John Eliot Gardiner's Schumann symphony set, with the Orchestre Révolutionnaire et Romantique. This set should, however, be tempting you. They're first-class performances in excellent sound, - and that ORR! The set includes the marvelous Konzertstück for Four Horns, both versions of the Fourth Symphony, and the "Zwickau" symphony. How can you possibly go wrong, for $29.99?