ORIGINAL: Ratzilla
Your cans are circa 1960, individually fairly a common can, $5 - $10 each in good condition like yours, but of course you've got the whole six pack plus the holder, too, so I'd guess about $50 for the lot - not bad for free! With the old can openers, it didn't matter which end you opened - but can collectors today prefer the bottom opened ones (because they still look unopened displayed upright). Nice find!