Your largest monthly expense will be rent and food.

I did a startup in another college town, and this is how it worked out:

- Rent - $1,000 / mo

- Food(3 guys) - $400 / mo

- Electricty (12 PCs/servers) - $150 / month

- Business internet access (hosted our own servers) - $150 / mo

Another big expense will be the incorporation costs, which can run as much as $500 (varies per state).

In the end, it ended up being $1,800 / person for the entire summer. We already had all the equipment, so none of that was included in the expenses.