I feel that there should be and alternative way to earn team donuts. Perhaps Hero Zero could offer team donuts for large sums of gold. I think the pricing should be expanded parallel to the expansion of the team. Maybe, since my old team had an expansion rate of 38% and a quarter level of 16 I feel that an appropriate formula would be 1000x(2^(y/10)) where x is the exp rate as a whole number and y is the quarter level. 1000(38(2^(16/10))) would come out to 115,194 team gold per donut for that team.

Currently on this team there is an exp of 66% and the quarter level is 24 so for my team now the cost of the donut would be 1000(66(2^(24/10))) or 384,350 coins.