Heh. I must have a more violent, impatient playing style -- involving both rapid expansion and peace through superior firepower.

If, say, you try to colonize one planet per turn (on average), and meanwhile try to build them all up, and then add ships for patrolling your borders, finding systems to colonize, and removing threats in the form of neighbors... it gets expensive. I've been spending just about every Last mineral on building facilities. I do need to scrap some of the older mining ships, 'tho.
In my present game (the one in which by sheer luck I got all three colony techs very VERY quickly) my construction expenses are pretty obscene, exacerbated by the fact that I put points into construction rate, and that I've got multiple conquered planets to population (had been fighting for most of the game, including turn 1. Conquered something like 2 neutrals, plus the Terrans, the Hive, the Xiloti (sp?), and the Pindons (sp?) so far, at least, of which the Terrans and the Xiloti both surrendered only very recently. These races were also quite fond of mines, meaning that a decent number of minesweepers was needed to make sure that my warships weren't obliterated on going through warp points.
In the meantime, I've also been pushing hard on research (working towards *good* phased shields, dreadnoughts, quantum engines and what-not), and trying to ramp up intelligence (because it'd be a shame if an AI managed to capture one of my prize CAs -- I've had the BC and BB techs for quite some time but haven't seen fit to build one yet; am waiting to get better tech to put in 'em). I could probably put together a nasty carrier, but I'm waiting for heavy carriers and better cargo tech. Why settle for only ~120 Large Rocket-Pod III Fighters?
(Hey. It's in character -- given that my portrait is of Vader, and the Empire wasn't known for tiny fleets of small ships.

)
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-- The thing that goes bump in the night