I think it was for The Blue Max (Goldsmith). I heard a suite on a compilation album that my father-in-law had and immediately tracked down the score. Not long afterwards I managed to tape the film on pay-tv.
The first film score I tried to buy pre-release was for Star Wars Episode 1, but this was in the early days of internet shopping and the good people of CDNOW (long since absorbed into Amazon) sent me the read-aloud children's book version instead. So by the time I returned it, got a credit and got around to buying it a real store, the film had opened. On the plus side I was spared the "noble end" controversy.