Dont know if this has been posted before.
Oh well. You'll find 2 guys in Darkmoon Faire named:
Professor Thaddeus Paleo
(Darkmoon faire Cards & Exotic goods)
Lhara
(Darkmoon faire Exotic goods)
They will have some limited supply items. Not sure about the spawntime though. but not that long, ive been there for like 2hours now and bought following:
8x Black Lotus(40s each)
2x Fel Lotus(4g each)
2x Nightseye(12g each)
1x Living Ruby(12g)
1x Dawnstone(12g)
1x Noble Topaz(12g)
5x Mote of Air(16s each)
4x Mote of Shadow(16s each)
6x Mote of Life(16s each)
2x Mote of Fire(16s each)
And ALOT of random herbs: Dreaming glory, Golden sansam, Terocone, Nightmare Vine, Felweed...
ENJOY!