Guilds have always been 10,000 DEC to create. It's one of the first burn mechanisms for DEC. After you create the guild you still need to contribute DEC to add or level up buildings. So guilds are tiered already by design. A level 1 guild cost 10,000 vs a level 2 guild which costs 20,000 (10,000 + 10,000) or a level 3 which costs 40,000 (10,000 + 10,000 + 20,000).