Apple invented, proprietary bullshit. No, you can't buy an SSD on newegg and slap it in. This, and the fact that the RAM IS SOLDERED IN... is why I can't stand Apple. They segregate themselves and frustrate all but the loyal, simple computer users. I love their design philosophy and butter-smooth software and user experience, I truly do... but the aforementioned issues are just too much.
Get the OWC drive, they have been making Apple-compatible high-quality parts for a very, very long time
:edit: though tbh I didn't realize at the time that there was this new, mSATA style SSD? I clicked on the above link, that would be interesting to see. I did read somewhere that Apple has no firmware limitations, so that crucial mSATA drive should, in theory, work!
:edit #2: of course the actual shape apple used is mSATA... but they had to take it a step further and modify the pinouts. Here is the picture of a normal mSATA pinout, the product you referred to earlier butlera. HERE is Apple's pinout on their Macbook Pro 13 Retina SSD.
YAY APPLE! Thanks for purposefully going out of your way to ensure a more expensive upgrade path, securing yourselves as supreme duechebags of the engineering world.