Maybe they are overpriced but they are by no means necessary to succeed. I haven't bought anything and am a duke and #1 on server 32, whereas most of the people that bought medal boxes to get ahead have a bunch of weak cities without the army/defense/research to match, and are juicy targets to be taken over and doled out to my alliance or barbed. Spending money will save you some farming time, or maybe get you out of a bad situation, but spending enough to have a complete supply of cash items and use them at every opportunity is so prohibitively expensive that only a few people do it serverwide, and even they aren't unstoppable.