Don't waste money on the various "Events" (i.e., Atomic Box, Top Secret, Naval Ammo Box). I think there's a bit of a scam, or at least a terrible "bait and switch" that GREE if foisting on people with these events. DO NOT WASTE GOLD on these events.
I had saved up 65 gold pieces and decided I'd try to win the Seawolf Class Destroyer (A/D = 289/244), which only requires 10 tokens to be found, so I figured at 15 gold pieces to open a box, I could open four boxes, so my chances over six days were good that I could get 10 tokens with free or medium openings. I opened one box with gold and got the token, but the second time I opened a box with gold, I was SHOCKED that instead of a token, I got some lame game piece (Dragon Solder, A/D = 20/15). Nowhere does GREE say that the boxes give you random items such as tokens, money, or other lessor valued game pieces. So, DO NOT WASTE GOLD on these events.
I hate to admit it, but I ventured another 15 gold pieces (they were free after all) a third time and this time I got $1,200,000 in cash. That was nice, but I wanted the tokens, not lame units or cash, so I realized that the game is probably rigged to not really allow you to get 10 tokens, but to entice you to try, perhaps tempting you to "buy" gold for more attempts. Halfway through the six day event, I've gotten 7 tokens, two cash prizes, and five lame units (2 ea. Dragon Soldier (20/15), Defensive Cannon (10/20), Ghost Hound (22/18), 2 ea. Armored Charger (12/14)).
At lest with the "Beat the Boss" events, they explain that there are prizes other than the three featured on the splash screen.