Custom Invoice for Customer?

So I have a customer that may want to purchase a fairly large amount of an item I manufacture.

1. Is it possible to send a customer an invoice on Amazon for such an order?

2. Is it possible to set a handling time of 4-6 weeks to allow time for the production of the products?

I would really not like to produce that many without the guarantee of the customer following through with their purchase by having them place the order only after they are ready to ship.... Any other platform, this task is super easy, but I am not sure it is even possible on Amazon?