How to find your model ID
You can use this page to locate your unique Mac Identifier Model.
Just follow the steps...
1/ About This Mac
Go to the Apple logo in the upper left corner and select "About This Mac"
2/ System Overview
Make note of the first part of your Mac model eg: MacBook Pro (13-inch, Mid 2012)
3/ System Report
Select the "System Report" button.
4/ Hardware Overview
Note down the Model Identifier eg: MacBookPro9,2 centre of page on the second line.
5/ Add the Mac model
MacBook Pro (13-inch, Mid 2012) and Model Identifier MacBookPro9,2 to give you your full Model Identifier number such as...
"MacBook Pro 2012 (Mid) Core i5 2.5Ghz 13-inch (MacBookPro9,2)"
6/ Now go to the Upgrade Selector
Select your Mac Family model, use your Mac model identifier that you just found, scroll down to your Mac model's year and select your model for pricing.