Paypal Button with Inventory - Can I have a discount and keep inventory up to date?

[lamarpta]

I have a store with multiple buy now buttons for merchandise. 

So for example: Tshirt - $12 in Sm, Med, Large, XL 

I want to offer offer that same Tshirt at a discount for $8 to a certain group of people. 
Is there any way to do that and still have the inventory stay correct?

Thank you!