hmm. If you need a gun that cheap, it could probably still be done...
maybe a single shot 12 or 20 gauge? Used hi point? Raven mp .25? Various derringers...
Prolly not something you'll be running billions of rounds through, but with that budget, not really something to worry about. You could probably get something that would work fine for a little practice, then stuffed away unless needed.
Kinda good to know even with 80 bucks you could arm yourself with something better than a louieville slugger