I would book directly through Carnival and just keep checking the price to see if there has been a price reduction. On categories that high, the price generally doesn't go down because there are few cabins in that class and they sell out before the cruiseline has to reduce price to entice sales.
If you book through a TA and something (anything) comes up, you can only deal with the TA, who may or may not have their own agenda. Once you book through a TA, most times the cruiseline will not deal with you directly.
For what it is worth, unless a TA is giving you some really great deal, it is easier to just deal directly with the cruiseline.
(cruzin' solo by design)
Freedom ('09), Imagination ('08), Victory ('08), Destiny ('08), RCCL Navigator ('08), RCCL Majesty ('08), Glory ('07), Liberty ('07), Fantasy ('07), Destiny ('06), NCL PofAm ('05), Fascination ('04), Victory ('04), Fascination ('04), RCCL Voyager ('03), Fantasy ('99)