The value of things.
To take better decisions in juggling resources, manufacturing, building, manpower, gold, ships, trade, and the like, you need to be able to attach a value so some things that are quite intangible at first glance.
Take a colonist for instance. Yes, it's hard to put a price on a human life, but for the purpose of winning in Colonization, it has a very tangible value: 600 Gold.
How do I figure that?
A city will pop out a settler once 200 food have accumulated, so 1 settler = 200 food. How much is 200 food? You can't look at the European prices for this good, because it has aberrant price dynamics.
In early gameplay, with no land improvements, a worker can get an average of 3.3 food per square farmed per turn. So 60 turns to build a settler. Had this worker done something else, like mine ore instead, for 60 turns, you would have gotten roughly 200 tons of ore, sold in Europe for about 3 # a ton, or 600 # total. That's the cost of building your settler: the value you could have gotten if you had built something else.
Try to buy a colonist in Europe. Train someone outright. The lowest cost specialist is the Ore Miner, at (you guessed it), 600 #. This is the game's way of telling you that 600 Gold is the minimum you can expect to pay to get a warm body now.
Sure, there is the option of "recruiting" which, you may notice, can provide lower cost manpower. But this manpower, like cannons, goes up in price for each time it is invoked. DON'T look at the price of the CURRENT recruit. That's just the price of buying off the balance of crosses remaining (in the "F2" screen) to pop out the current emigrant. (this price may be deceptively low). BUY the first one, then BUY the SECOND, AND the THIRD after him. Look at THOSE prices. As those price tags escalate beyond 600 #, it becomes wasteful to recruit, since cheaper people can be had by TRAINING.
Do, by all means, procure all your early manpower by recruiting, and paying premiums for recruits, so long as you're not paying over 600 Gold. But once recruit prices do get to 600 #, your Ore Miner will be your best bet for new colonist purchases. ( you will need to "clear specialty" once in a New World town, if you want to re-train him to do something else.)
The takeaway from this: 600 Gold is the nominal price of a colonist (specialty aside). ANYTIME you can get one for less than that, go for it; it's a bargain.
Takeaway Nr 2:
The value of a Fountain of Youth ( 8 colonists ) is a base 4800 Gold.
For those of you using the save/reload cheat before hitting Rumor Goodies, you can compare the Fountain of Youth to a treasure wagon of a very specific value.
This actual value will be higher than the nominal 4800 #. Your tax rate, for instance, imposed on the treasure, not imposed on the Fountain bounty. Now we're looking at 5300 # or so. Then there are the valuables some emigrants may be carrying with them, like tools, guns, or horses. On average I've noted about 500 # in value. And then there may be some really useful specialists, like Scouts, Pioneers, Veteran Soldiers, or Statesmen, that make your mouth water, especially if you've gotten none before this. Add another 500 # at a conservative estimate.
So a Fountain of Youth may be worth at least 6300 Gold in equivalent treasure, more if you're in a high tax bracket. Only a City of Cibola with a 7000 Gold bounty may even compete with it. Do not pass it up.
Whenever money permits, buy as many colonists as you can from Europe, as early in the game as you can. Do not try to pop out colonists in cities in the first 100 turns by building food. It is a poor use of manpower for fast development.