Well, I have seen only a few times some new unopened blister packs of the knights of the blazing pack but their price was exteremely high (like 28-30€ per blister pack, which contained around 8 heads if I am not mistaken)! For me that price is insane! It comes cheaper if you buy the whole blazing sun knights (more possible to find, thanjust their bits)! I would really love to have those upgrades for some cool conversions, but never at such prices...