Is because it was not reissued for a long period of time and it represent Rodimus not hot rod. The TRU "hot Rod" version was supposed to be better build but even then I know someone who broke a joint on that version. This was one of the worse MP till date but I know some people who love it.
I simply dont like it that I could not get him to hold his gun, or have him pose properly. Not to mention ver 1 have a bad backpack issue that it doesn't clip on.
The new hot rod on the other hand was a better overall figure, the only down side was that it hardly was able to roll in vehicle mode. Otherwise a better attempt. But it isn't Rodimus prime
Most masterpieces sky rocket in prices are only due to the fact that a reissue was not done for a long period of time.