No offence but... these memory sticks are obsolete and Sony won't be producing them much longer. Why not buy a normal SD card instead of this outdated technology?
MS are hard to get and way too expensive... with an SD card you get even more GB for even less money....
my tip:
Sandisk Extreme Pro SDHC UHS-I (16GB, Class 10)

This camera produces images that take up very little space. Meaning, don't buy big memory cards... at most a 16Gb... that's enough for thousands of pictures... even that is too much....
imagine if the card is defective... the camera gets broken or stolen.
I don't work with too big cards even with SLR... I'd rather have 1-2 cards that take up practically no space than one big one where I run the risk of losing ALL my pictures at once ;)
Any photographer will tell you that.