Calculator for bulk items

I will be using Zen Cart for both items to sell and items that will appear only for informational purposes that I do not wish to ship, but do sell every day in our store.

Some of the informational items are sold in bulk and while the quantity discounts are helpful in showing the pricing levels, it does not display what the total cost would be. For example, if someone wanted 45 widgets at $1.31 each, the price would be $58.95. I do not expect most people to be able to determine these figures in their head and I am hoping that there is some sort of calculator script or plugin I can add to these pages to make this easier.

I know that the customer could enter the desired quantity and look in their shopping cart for a total, but I will be disabling the "add to cart" aspect of these informational items. (I am actually entering these items as a "Document - Product" so that I can manage those pages apart from the for sale items.)

So, any ideas?