I had this quest once. It was bugged at that time so I never got the payment (I'm not sure whether the bug has been removed in 3.13; I hope so though it doesn't appear to be in the change log). But I found it worth it, because the result was sevaral colonies and some extremely useful resources, principally oil, that I didn't have at home. These can be especially useful with the arrival of corporations. I avoided ruining my economy by not founding all the cities at once on the same contintent (the cost for one city on a foreign continent is not expensive). Where there was a risk of someone else founding a city, I did have more than one on a continent, though. For other cities, I simply sent out settlers, with due protection, and waited till they were all in place to build the cities all at one and the same time. After that, when it was clear that due to the bug I wasn't going to get any reward for my labours, I simply turned them into colonies, and went on to win the game regardless.