I'd look for something that is STI approved - that means it passes for racing applications.
I look at safety this way, why the hell would you ever want to cut corners on something that may need to protect your life ?? Why the hell do people trust the stock car style seat belts!!
back in the day when I worked at the store level, I'd have customers (industrial) come in and ask about safety glasses - I'd go over and try to get them to try them on to see what fit best, and most of the time they'd just one the cheapest they could find.
Eyeballs, arms, legs, YOUR LIFE........ are not replaceable.
not to sound like a dick, but spend the money on proper safety equipment, your life may depend on it.
take it from someone who HAS been airlifted out of the desert, you dress for the crash, not for the ride.