It's free to stream in a number of places, but you can buy it too. Most places only sell the English dub digitally and it costs more than the bluray/dvd anyway, so I'd recommend picking those up. Sets 5,6,7 cover the Chimera Ant arc until the end:

set 5

set 6

set 7

Target, Walmart, B&N, Bestbuy, Rightstuf, etc. also carry the sets.

And there's a complete series boxset on bluray, if you're interested.