[R-390] Negative temperature coefficient capacitors

[Larry H]

I'm in need of a few negative temperature coefficient capacitors.  I've found some on Mouser in small quantities, but not very many and not the values I'm looking for.  Specifically, I'm looking for 50 pf @ N500 or N600 or a 100 pf @ N1400 or N1500.  The voltage needs to be 100 or higher.  I'd like to reduce the 'warm-up' drift of my BFO.  In my search for them I came across information that the dielectric R3L = N2200, P3K = N1500, and U2J = N750.  Can anyone substantiate that or add to it?  DigiKey has a lot, but their minimum purchase of each is 1000 or 2000.  Too many for me.  Any ideas where else I can get them in small quantities?  Thanks.
Love the Kielbasa.
Regards, Larry