$6 or $50 cam locks?

[Ketchgould]

Talking about the keyed cam locks for locking my new teak cockpit benches...

I want to install cam locks in the benches to lock them closed rather than use the padlock style as the protrude enough to bang your shin enough. A cam lock that is zinc yet made by sea dog or Sierra for exterior use is about 6 bucks. A solid brass one by Illinois lock company is fifty bucks. Our boat is used in fresh water on Lake Superior, will the zinc lock work or last long enough anyway?

Thanks. Down to my last few boat dollars...