How would i deal with doing a drop down menu like this?

A product sells by wholesale, in units of

8 units @ 1.00 each
16 units @ .95 each
32 units @ .75 each

I already wrote the code to do a drop down menu for choices, but not for different prices with different number of units.

You can see this http://www.jkedistributors.com

How would I accomplish a different price for different quantities being purchased?