actually these are on super special after instant code it's only $103. I figured spend the extra money now and be future proof for a while.
It's still an awful deal at $100. The difference between this memory and a standard 8GB kit for $40 is very, very, very
small. My computer rarely exceeds 60% memory usage with 8GB, and that's with a game, Firefox + dozens of tabs, visual studio, an FTP server, media server and tons of other little utilities running simultaneously.
Getting 16GB will just mean you have 12GB of memory sitting around doing nothing instead of 4. By the time you need that extra memory, it's going to be horribly out of date.
I'd strongly recommend saving the money and getting 8GB of DDR3-1600, or even 1333.