Theorically, It should be 250, cuz the ****ing AA top upgraded base were 272+, so stop crying like a baby.
Buy crown, upgrade every bulding, including farms and caravans AND roads. Make a sheet, study the game and grow up.
You find intelligent to suggest buying over 500$ to 1000$ (USD) of crowns to follow your very smart suggestion...
Did you work for Nexon (or you have a % on crown buy by player)...
Your suggestion is the less "intelligent" comment I have read here...