There are loads of different kinds of salt available: Italian, French, gray, green, pink, smoked, etc. If you're going to make my chocolate and salted-caramel cookies, choose a brand that is the right price for you and that you're likely to use again.
My recipe calls for only a pinch of salt per dough ball, so don't feel like you have to buy a huge amount of the stuff. But whatever you do, do not use regular iodized table salt or kosher salt in place of the sea salt. You'll end up with a cookie that is spit-takingly salty.