How about the MMDL301T1G as a sampling diode? The datasheet says the typical capacitance is 0.9 pF, the minority carrier lifetime is typically 15 ps, and a reverse leakage of typically 13 nADC. They're also $10 for 100 on Digikey (or $0.25/each), with 150K shown as available anywhere on Octopart.
The Avago quad bridge diodes, HSMS-282P-TR1G seems to be going fast on Digikey, there were about 3K a few days ago and I just bough 20 (as I've been toying with sampler ideas), with less than 500 left. Mouser still has about 800. The plus of the multi-device package is the diodes are claimed to be better matched, which is good for a sampling bridge.
Jan