We have these for OS and for recording and for samples.
http://www.amazon.com/Samsung-Electr.../dp/B009NB8WRU
And then we have these aswell. Better price but basically no difference in speed. Very good performance for the money.
http://www.amazon.com/Samsung-250GB-.../dp/B00E3W1726
Of course there are other SSD's that works great but as we only invested in Samsung thats the only ones I can Vouch for.
These enclosures will do the job very well and less than $15 too
http://www.amazon.com/Anker-Drive-Ex.../dp/B00H98AXOE
And these are Thunderbolt and more expensive (we have them in our big studio but the USB3 cases are very good for PT use)
http://www.amazon.com/StarTech-com-E...M3C5WQSF1Z9TJ9
This is way better priced for single thunderbolt external ssd case:
http://www.amazon.com/Delock-Externa...M3C5WQSF1Z9TJ9
There are lots of enclosure cases that works great but these are the exact ones we have now and have used before so thats why I posted the links to them.
Here is a all-in-one that we have friends who use everyday and have super good build quality. A little more expensive than getting an SSD and a external case but it is an option for you:
http://www.amazon.com/LaCie-Rugged-T...A2WW9DSYAK9QFP
Best
Christopher