Reddit reviews Complete Webern [6 CD Box Set]

A few to consider, some more affordable than others:

• Complete Webern
  
• Complete Varese
  
• The DG Complete Beethoven Edition (if you can find it anywhere)
  
• The Philips Complete Mozart Edition (if you can find it anywhere)
  
• Steve Reich
  
• Philip Glass
  
• Handel - Orchestral Works
  
• Bach - Orchestral Works
  
• Ravel - Complete Edition
  
• Debussy - Complete Edition
  
• Shostakovich Edition (one of the few Brilliant Classics box sets I can wholeheartedly recommend, unlike many of the others which can be a bit patchy)
  
• Strauss - Complete operas
  
• Wagner - Complete operas (Solti)
  
• Boulez - Bartok
  
• Boulez conducts Schoenberg (far from complete, but this about the best you can do)
  
• Boulez - Stravinsky
  
• Various Bach choral stuff - Gardiner
  
• Stravinsky
  
• Alban Berg Collection
  
• Berlioz - Complete orchestral works (Davis)
  
• Brahms - Complete Edition (absolutely superb collection)
  
• Britten conducts Britten + operas 1 and operas 2 + Complete Britten
  
• Sibelius - Symphonies and tone poems
  
• Elgar - Collector's Edition
  
• Vaughan Williams - Collector's Edition
  
• Barber - orchestral works (Alsop)
  
• Scriabin - Piano works
  
• C.P.E. Bach Edition
  
• Corelli - Complete Works
  
• Telemann - Tafelmusik
  
• Schubert - Masterworks (Brilliant Classics - not always the best recordings, but for the amount of stuff you get, worth the money
  
• Poulenc - complete works
  
• Messiaen - complete edition
  
• Mahler - complete edition (the symphony recordings here are a representative cross-section, you might want to supplement it with another complete cycle, e.g. Solti, Bernstein, Abbado, etc.)
  
• Liszt - Complete piano music
  
• Janacek - Operas
  
• Haydn - Symphonies (Hogwood), not complete, but as close as anyone has come to it
  
• Mozart - Symphonies (Pinnock) - an alternative to Mackerras
  
• Bartok - Piano works
  
• Debussy - Piano works
  
  If you need anything more specific than that, let me know and I'll try to recommend something.
  
  If you have a look in the "Customers Who Bought This Item Also Bought" section for any of these, you'll find many more.

Pierre Boulez’s “Complete Webern”, and the LaSalle Quartet's set of Second Viennese School quartets.

Also, Mitsuko Uchida's complete Mozart Sonatas.