Prohibition on selling blood

This is regarded as selling blood, and selling blood is
haraam according to scholarly consensus. 

It says in Fataawa al-Lajnah al-‘Daa’imah li’l-Buhooth
al-‘Ilmiyyah wa’l-Ifta’ (13/71): 

It is not permissible to sell blood, because of the report in
Saheeh al-Bukhaari from Abu Juhayfah who said that he bought a cupper
(as a slave) and ordered that his equipment be broken. He was asked about
that and he said: The Messenger of Allaah (peace and blessings of
Allaah be upon him) forbade the price of blood. 

Al-Haafiz said in al-Fath: What is meant is that it is
haraam to sell blood just as it is haraam to sell dead meat and pork, and it
is haraam according to scholarly consensus, i.e., to sell blood and take its
price. End quote. 

It says in al-Mawsoo’ah al-Fiqhiyyah (9/148): 

It is haraam and, the contract is invalid, to sell “blood
poured forth” because Allaah says (interpretation of the meaning):  “… or
blood poured forth (by slaughtering or the like),” [al-An’aam 6:145].
Ibn al-Mundhir and al-Shawkaani stated that there was consensus among the
scholars on the prohibition on selling blood. End quote.