I think that is more to do with "newness factor" than anything, ie people get new toys and want to show them off. Since ROC and 25th are newest people show them off while its really hard to get new ARAH if you have been at it for a while even on the second hand market since there is a finite number of figures. Whereas ROC and 25th are still coming out.
Just a thought. I know I do that from time to time
