You purchase a serial number for Premiere Elements 12 from Adobe or shop around.
Premiere Elements 11 and 12 are standalone products.
You could contact Adobe Customer Service about "deals". But, I suspect your deal will be that of any other, that is, a pricing consistent with a person who has been using a prior version of the product.
If you want to contact Adobe via its Adobe Chat to discuss this matter, then click on the following link, and, when it opens, click on "I still need help" to bring up the Adobe Chat.