The colony was so far from my capital that it was only going to produce one shield per turn. So waiting one turn wouldn't have halved the price of harbor, only reduced the cost by about 4 gold. On the other hand I really needed that silk resource (look underneath the settler's feet) and I didn't want to risk losing the settlement by cultureflip to the Germans or French whose cultural centers are very very close by. In this scenario I really hate the French. So yeh, it cost me a bundle. But I was already running a nice fat budget surplus (cause I'm not a Republican ) and having that colony shipping silk into my big cities really happied up my citizens.