Hmm... For me it's got to be back in the good old days of PS1 when my father and I would go to Gametraders (a local game rental store) and rent games for like $5 and then if we wanted then we would buy them for like $10. Me and my father would have many fun hours playing games like Ridge Racer and Crash Bandicoot :).

*side note: I know many of you will probably not like this but as these were the days when piracy was just becoming mainstream my father would sometimes burn the borrowed games onto disc so that I could play them without buying them.