It would be great, if you would pay the 60-70$ extra fee for the name "Apple" - that would make a small sense - but you didn't even that.
In my Mini was "Hynix" branded RAM installed and i replaced it with RAM from Samsung (harrharr, take this, apple!). In other (older) Minis i've found RAM from Transcend or Crucial.
Apple bought what they can get for low prices.
An 70$ extra fee for less than 5 mins of work (not mentioned that apple don't have to pay 30$ for 2x4GB of RAM) i would only pay, if i knew that the money is directly given to the workers in Taiwan who build my Mac Mini.
Since Apple uses the Intel x86-Plattform for their Macs, you can install every "PC related" RAM modules.
You only have to look at the specs. For the model "late 2012" you should only use DDR3-1600 (aka PC 12800), because the processor is able to handle RAM at that speed. With older DDR3-1333 (or less) modules you will get a significant lower performance.