yea, was looking for them on ebay too, and taobao, seems like taobao has them for the lowest price at the moment but they tend not to have stock (even when it says 4 pieces left)
全新原装HP ML350P GEN8 G8散热片,667268-001,661379-001 现货
全新 HP ML350p Gen8 风扇667254-001+散热器667266-001 升级套件
Probably more...