We get this question all the time from our new members - which glasses to buy.
You can find certified glasses anywhere, and at any price, from $2 on up. The price has very little (or nothing) to do with the lense's ability to stop a BB. Certified is certified. It all comes down to comfort and style.
Obviously, they need to wrap sufficiently to virtually eliminate the possibility of a BB sneaking around the side, or coming in from above or below the lense, but other than that, whatever fits best, fogs least, and works best for you is just fine.