Is it worth spending the money?
I am not sure if you are asking whether it's worth spending the $33.98 for the fan mod or the $469.99 for the case ? In either case, I'd say no though. An Antec 1200 or HAF 932 will provide way more than adequate cooling at 1/3 the cost.
And while 120mm fans are generally quieter than 80's, with that many fans and that open a case, it wouldn't matter.