Best Computer for Hacking

I know Kali Linux can be installed on various computers but I'm looking for a really good computer to use for Kali. Currently I'm using my Mac to run it along side OS X but I only have around a 125 GBs of storage so I don't have much room for Kali. I was thinking of going with maybe a Alienware because its a super fast computer but I really don't feel like spending so much money on a computer. So if someone could recommend a reasonably priced computer around 500 dollars preferably a small computer around 10-13 inches thats pretty fast that would be great. Thanks!