To translate a bit for the Brits - I think the expected standard here will be ABRMS7/8, as the Eccles sonata in the book Kev found used to be in the Grade 7 syllabus - I did it for my A-level recital many moons ago...
Other suggestions for the more classical end of the spectrum at this level - "15 Etudes by Charles Koechlin" should have plenty to go at (and are really good for practicing since each focusses on a different aspect!!).
As Tom says, the James Rae library is pretty extensive and technically very good.
Maybe try some of Lennie Niehaus' jazz etudes too for the jazz audition, though make sure it's advanced enough! Another book I use in the UK is "Sax Scorchers" (ed. Nigel Wood, pub. Saxtet), Salon de Destrabe in there is hard but good, and my favourite in that book is Atlantic Day which will blow away the panel if you nail it!
Questions to ask:
Check you've some idea of the technical level they're expecting (and that it matches these suggestions!) - ask for examples of pieces other applicants have played in the past;
Ask if they require an element of improvising too;
Check the duration they're expecting - don't turn up with fifteen minutes prepared if they're expecting six, or vice versa!
Good luck,
Nick