Would it be possible to just buy it with the lowest amount of memory, and then just putting in 16 gigs yourself? (trying to save money)
Sure it's possible!
If you have a source for 4x4Gb sticks for less than $1400 go for it!
Nice!
However, for my use I think I'll stick to 8 GB for $120.
Wow 8GB for 120? Where? >_<"?
You probably would not see a lot of performance gains from anything over 6GB.
As true as that statement is, the amount of RAM you have is directly related to the applications you are running. So if you wanted to use Photoshop other other memory intensive applications on the Mac AND run a Virtual Machine with enough left over memory, something like 8GB or even 16GB would work out fine..
Remember, OS' will use whatever memory you throw at them and yes system performance doesn't increase with more RAM, but system responsiveness increases greatly..
Regards
You probably would not see a lot of performance gains from anything over 6GB.