The best way to get territories is by 10 at a time. Problem is planning ahead. So this should help some of you. With this, you'll know what to save up for in advance.
Skyscrapers:
10 costs 200M
20 costs 400M
30 costs 600M
40 costs 800M
50 costs 1Bil
60 costs 1.2B
70 costs 1.4B
80 costs 1.6B
90 costs 1.8B
100 costs 2Bil
Casinos:
10 costs 500M
20 costs 1Bil
30 costs 1.5B
40 costs 2B
50 costs 2.5B
60 costs 3B
70 costs 3.5B
80 costs 4B
90 costs 4.5B
100 costs 5B
Outlet Shopping Strips:
10 costs 750M
20 costs 1.5B
30 costs 2.25B
40 costs 3B
50 costs 3.75B
60 costs 4.5B
70 costs 5.25B
80 costs 6B
90 costs 6.75B
100 costs 7.5B
Office Buildings:
10 costs 1.25B
20 costs 2.5B
30 costs 3.75B
40 costs 5B
50 costs 6.25B
60 costs 7.5B
70 costs 8.75B
80 costs 10B
90 costs 11.25B
100 costs 12.5B