Here is my 2c, If it cost 20 for the springs and you stated the tank will be heavier, that will put more stress on the plastic arms also which in turn most likely will break. The metal arms are around $30 I think, now include shipping you are looking at $60 to $70 for springs and arms. I would spend $30 more then that and get the asiatam hull. Metal arms,bearings etc are included I believe.

Cheers,
Wade