My friend and I are going to write a multiplayer, multiplatform RTS game and are currently analyzing the costs of going with a client-server architecture.

The game will have a small map with mostly characters, not buildings (think of DotA or League of Legends). The authoritative game logic will run on the server and message packet sizes will be highly optimized.

We'd like to know approximately how much server bandwidth our proposed RTS game would use on a monthly basis, considering these theoretical constants:

1. 100 concurrent users maximum
2. 8 players maximum per game
3. 10 ticks per second

Bonus: If you can tell us approximately how much server RAM this kind of game would use that would also help a great deal.

Thanks in advance.