When I lived in BC, I used to use a mag stripe-based system to use the busses and trains in Vancouver. The cool thing was that you can buy these cards that are already set to travel within their allowed zones. However, a flaw in the cards was that they contained no set cash value in the mag stripe's data, so if they raised the prices, provided that you have an older unused card, you could buy a 1-zone card for $2.25, and when they raised it to $2.50, the card would still be valid since it has no value.
To make it effective and not to get caught, you'd just use a ticket machine to upgrade the card to a 2 or 3-zone card.