Share 'Heirloom seed question'

Can anyone tell me if there is a way to tell if seeds bought at the local stores etc, are heirloom or hybrid? I know sometimes the package will say if they are a hybrid or not. I want to start saving my seeds, but can't really afford to pay for heirloom seed ordered special. I would love to, but our finances just won't allow it. I have a lot of seeds I have saved over from previous years (keep co…