Just as Eliana said, 3000 BEE for the functionality of a very basic tribe, and then stake 1 BEE for every active user.
If you want delegations then that is an additional 1000 BEE, and to get miners you need 1000 BEE to enable staking and another 1000 for the mining contract.
Each token also cost 100 BEE to create too.