For the Fleet Ship Modules alone, that's a price of 2000 zen, or 22000000 Engery Credits (at last count). Fleet Credits are easier to come by; all one must do is contribute.
The big question though, is the purchase worth it? I'm an Engineering toon, currently flying a Patrol Escort (I find them more fun to play at the moment). The only Fleet Ship I've ever been truly interested in is the Fleet Assault Cruiser, more specifically the Lt. Cmd Tactical Slot (armed with Torp HY3 or Torp Spread 3 most likely).
Still, for the sake of that alone, added with an extra Tactical Slot and a new Ship Skin (of which I wont be using any of as I deem the Imperial Class/Skin ugly) does the cost warrant the purchase? Sure, I get a bit of a hull and shield buff, along with the already mentioned tactical console slot, but I'm not sure whether the actual price warrants the purchase.
I've already got the Assault Cruiser (and Mirror Star Cruiser) so I've got everything that I'd use on the cosmetic scene. I'm probably going to respec my toon soon so that he's more ENG-orientated (he's kind of all over the place at the moment).
But yeah, yay or nay to the Fleet Assault Cruiser?