Signal Generator HP/Agilent 8664A has -140 dBc/Hz typical SSB phase noise at 20 kHz offset at 1 GHz with Option 004. Now depend what offset are you looking for -150dBc/Hz.
This is a well-known low phase noise crystal oscillator from ADI: **broken link removed**
which has –138dBc/Hz at 1kHz.
Assuming 10dB/decade slope, the phase noise could be close to your target.
Also you can try this oscillator:
**broken link removed**