Should I keep buying gift cards for the discount?

I work upstairs from a location  of Lee’s Deli, so I go there a lot for lunch. They have a deal where if you pay $50 for a gift card, they’ll load it with $55 of value. Sounds like a good idea, right? But on the other hand, I’m not going to stay at this job forever, so at some point I’m going to end up stuck with value on one of my cards. Should I make a habit of buying these cards?

On the one hand, for every card I buy I gain $5 in value.

On the other hand, I expect the card that I have when I will no longer need such cards will have half of its $55 value left when I leave, costing me $27.50.

So if I expect to stick around long enough that I’ll go through five and a half gift cards – spending $302.50 – then I should keep buying the cards.

Of course, in reality, I won’t use this analysis, because:
– when I do leave my job I won’t just walk out the door; I’ll give some notice, like you do. So I can decide to use up the card.
– if worse comes to worse, I can sell the card to someone else in the office, at least at face value – I’m not the only one who buys these cards.