Can I negotiate with a customer and come up with a discount?

Yes, make sure you are part of the sales team. You can do everything you can to close the deal with the customer.

Try to choose your common sense so you can negotiate with the client.

Once the customer is interested, all our products are on our Shopify Store. Simply send the product link to the customer, and he can place the order on the online store.

Likewise, you can send an invoice to him. Here's how to do it

How to send an invoice to a customer?