Hi Shauntea and welcome to the forum,
If the products have prices clearly displayed online, then I wouldn't be sending the customer anything. Only referring him to the listed prices on the website (as it seems you have already done)
If he is talking about discounts, then you need to ask him for details regarding his intended purchase. For example, how many different products is he wanting to purchase and how many of each?
Then what you can do is go to your supplier and give them those numbers and see if they can give you a better price based on them. Then you can make your original markup and pass the discount (if there is one forthcoming from the supplier) on to the customer.
If the customer is just wanting to get a discount on a single item, then don't waste your time on them. Tell them the prices are displayed on the website and there are no discounts for single item purchases, that's all you need to do.