The Emu Proteus 2 is labeled the "Orchestral" Model so you may want to check that one out. You can certainly get one in like-new condition for less than $300 on ebay.
The Roland JV-1080 also has GREAT orchestra sounds with the orchestra expansion card. but the synth is $500ish used and the expansion cards are around $140, so i guess that is a little out of your price range.