I wait until Tapjoy’s offering double rewards, then go crazy on it. I get 4500 cash for the coin vault. I’ve only spent about 1000 cash on other things in my 7 months of gameplay. I’m nearly level 16 with a mostly level 19-20 crew, and I still haven’t run out of coins. I haven’t been busy saving my coins, either. Only 3 of my dinos aren’t level 11 yet (I got them there for experience) and I’ve got a fair few at level 15. I’m not leveling the Proceratomimus for combat because I don’t want to pay the coins, but I think that’s the only thing I’m missing right now. I’m also frequently opening the 5 supply drops stationed around my dorm and taking all the strike events, so even without Tapjoy I don’t lose coins very fast.