lighting is the big killer, when it comes to changing DA's council regulations and requirements in regards to access, toilets etc can also substantially increase the costs, and depending on what sort of irrigation/drainage system you want it could go either way as well..
Dont ignore the development costs associated either, this often turns into a costly and timely process as well, and if you are like Souths Rugby Club in Brisbane, the approval process itself could almost send you teetering on the edge of bankruptcy even before the field is constructed.