Chosen Solution

I have a MacBook Pro Retina (10,1) mid 2012 A1398 EMC2512 that came equipped with 256GB SSD . Running out of space and find the OWC and Transcend brands to be quite expensive. Which Samsung or any other reliable mainstream brand 1TB drive would be compatible with this model and what connector, case and other things will I need to install it?

Here is the SSD that is recommended by iFixit (You can choose the size). Here is the guide including which has a list of all the tools you will need to do the replacement. Hope this helps, Tariq!