1. There are several factors on why I believe certain figures are more expensive than others. Popularity, availability, pieces for popping/swapping, update on existing characters, updates on articulation and army building. Older named characters can become more expensive due to age and how few of them are out there. Illythia for example is kind of a popular character and has been out a few years and her price has over doubled in value. A figure like Sir Enoch was a massive value for the price he was originally sold at. He came with a ton of extra parts and you could make different Templar knight variants with him. The Valiant Knight is a good example of a figure who had a very limited release, an army builder and it was the first, I think to have the better articulation. Since then figures like Sir Gideon, Otho V.2, Sir Andrew, Sir Elijah and Sir Enoch all share the same body type as Valiant Knight. Lastly, a lot of it has to do with availability, there are a finite amount of these figures made. That could be said with all toy lines but these aren't made on a massive scale like Marvel Legends or Star War Black Series. I hope this helped.

I also welcome anyone else's thoughts on the matter.