Hi naaman, as you point out the HREE are more expensive than...

Hi naaman, as you point out the HREE are more expensive than NdPr but that is because they are found in smaller quantities in the REE basket and usually have a smaller commercial market. The elements you mention, Lutetium, Thulium, Holmium (amongst others) are typically only used in research and other scientific experiments such as prototyping and advanced scientific test equipment whereas NdPr has an established market in the electrical and technology sectors. Dysprosium and Terbium have also carved out a place in these sectors although again because of the smaller quantities available the prices are high. Just recently I heard the scientists are now looking at mixing Lanthanum and or Cerium (because of their abundance) with the Dysprosium and Terbium to stretch out the supplies as current commercial demand for these elements outweighs the supply.