Everyone's circumstances are different, but I've never bought a season ticket because it saved me money, I've always bought one as a donation to the club I love, which just happens to come with a bonus of free entry to some games...season tickets allow clubs to better budget for squads v's pay-at-the-gate...
I do, though, appreciate that money is tight so fair play to those who feel pay at the gate offers better value for money, but if value for money is what you're looking for, there is an argument that 17quid at Firhill is a rip-off!!