Manually manage orders without online payment

One of my customers has requested to restrict the possibility for users of a certain country of paying online an order.

Users of this country should instead:
– put articles in the cart,
– fill out the shipping form,
– having the order sent via email to the merchant for manual completion (no online payment of any sort).

The whole point is making sure that the merchant can send a manual and customized shipping offer to the users of that country.

Is there any way of achieving this ? Thank you in advance